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Rational design and synthesis of Cr_(1-x)Te/Ag_(2)Te composites for solid-state thermoelectromagnetic cooling near room temperature

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Chinese Physics B 2024年第5期33卷 580-586页

作者：孙笑晨谢承昊陈思汗万京伟谭刚健唐新峰 State Key Laboratory of advanced technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China International school of Materials science & Engineering Wuhan University of TechnologyWuhan 430070China

Materials with both large magnetocaloric response and high thermoelectric performance are of vital importance for all-solid-state thermoelectromagnetic *** two properties,however,hardly coexist in single phase materials except previously reported hexagonal Cr_(1-x)Te half metal where a relatively high magnetic entropy change(-△S_(M))of~2.4 J·kg^(-1)·K^(-1)@5 T and a moderate thermoelectric figure of merit(ZT)of~1.2×10^(-2)@300 K are simultaneously *** we aim to increase the thermoelectric performance of Cr_(1-x)Te by compositing with semiconducting Ag_(2)*** is discovered that the in-situ synthesis of Cr_(1-x)Te/Ag_(2)Te composites by reacting their constitute elements above melting temperatures is unsuccessful because of strong phase ***,at elevated temperatures(T>800 K),Cr_(1-x)Te has a much lower deformation energy than Ag_(2)Te and tends to become more Cr-deficient by capturing Te from Ag_(2)***,Ag is insufficiently reacted and as a metal it deteriorates *** then rationalize the synthesis of Cr_(1-x)Te/Ag_(2)Te composites by ex-situ mix of the pre-prepared Cr_(1-x)Te and Ag_(2)Te binary compounds followed by densification at a low sintering temperature of 573 K under a pressure of 3.5 *** show that by compositing with 7 mol%Ag_(2)Te,the Seebeck coefficient of Cr_(1-x)Te is largely increased while the lattice thermal conductivity is considerably reduced,leading to 72%improvement of *** comparison,-△S_(M)is only slightly reduced by 10%in the *** work demonstrates the potential of Cr_(1-x)Te/Ag_(2)Te composites for thermoelectromagnetic cooling.

关键词： thermoelectromagnetic cooling thermoelectric magnetocaloric composite chromium telluride

Engineering Thermoelectric Performance of α-GeTe by Ferroelectric Distortion

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Energy & Environmental Materials 2024年第2期7卷 171-179页

作者： Yuting Fan Chenghao Xie Jun Li Xiangyu Meng Jinchang Sun Jinsong Wu Xinfeng Tang Gangjian Tan State Key Laboratory of advanced technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China International school of Materials science and Engineering Wuhan University of TechnologyWuhan 430070China

The rhombohedralα-GeTe can be approximated as a slightly distorted rock-salt structure along its[111]direction and possesses superb thermoelectric ***,the role of such a ferroelectric-like structural distortion on its transport properties remains ***,we performed a systematic study on the crystal structure and electronic band structure evolutions of Ge_(1-x)Sn_(x)Te alloys where the degree of ferroelectric distortion is continuously *** is revealed that the band gap is maximized while multiple valence bands are converged at x=0.6,where the ferroelectric distortion is the least but still *** undistorted,the band gap is considerably reduced,and the valence bands are largely separated ***,near the ferro-to-paraelectric phase transition Curie temperature,the lattice thermal conductivity reaches its minima because of significant lattice softening enabled by ferroelectric *** predict a peak ZT value of 2.6 at 673 K inα-GeTe by use of proper dopants which are powerful in suppressing the excess hole concentrations but meanwhile exert little influence on the ferroelectric distortion.

关键词： electronic band structures ferroelectric distortion lattice softening thermoelectric α-GeTe

Effect of Ti_(p) Content on the Work Hardening and Softening Behavior of Mg-Zn-Ca Alloy

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 551-560页

作者： Jin-Kai Zhang Cui-Ju Wang Yi-Dan Fan Chao Xu Kai-Bo Nie Kun-Kun Deng Shanxi Key Laboratory of advanced Magnesium-Based Materials College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan 030024China school of Materials science and Engineering Harbin Institute of TechnologyHarbin 150001China

The Ti_(p)/ZX60 composites with different Ti_(p) contents were prepared by semi-solid stirring *** extrusion,the microstructure,work hardening and softening behavior of the Ti_(p)/ZX60 composites were analyzed compared with the ZX60(Mg-6Zn-0.2Ca)*** results showed that the addition of Ti_(p) could not only promote the nucleation of dynamic recrystallized(DRXed)grains,but also be propitious to the refinement of DRXed *** increasing Ti_(p) content,the size of DRXed grains decreased accompanied with increasing volume fraction of DRXed *** the Ti_(p) content increased to 15 vol.%,the average size and volume fraction of DRXed grains reached to~0.32μm and 93.2%,***,both the strength and elongation were improved by the addition of Ti_(p).With increasing content of Ti_(p),a substantial increase in the strength was achieved with little change in the ***,the elongation decreased sharply when the Ti_(p) content further increased to 15 vol.%.The addition of Ti_(p) led to an increase in the work hardening rate,which gradually increased with increasing Ti_(p) ***,the softening rate did not demonstrate the same tendency with increasing Ti_(p) *** the conventional ceramic particles,the Ti_(p) can be deformed in coordination with the matrix alloy,which imparted a higher softening rate to the matrix *** though the softening rate improved as the Ti_(p) content increased from 5 to 10 vol.%,it dropped deeply as the Ti_(p) content increased to 15 vol.%owing to the fracture of Ti_(p) during extrusion.

关键词： Titanium particle content Particle reinforced magnesium matrix composites Work hardening Softening behavior Mechanical properties

Hot deformation behavior and microstructure evolution of GH3536-TiB_(2) composites fabricated by powder metallurgy

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science China(Technological sciences) 2024年第7期67卷 2107-2124页

作者： ZHOU ShiPeng WANG Shuai HUANG LuJun ZHANG Rui CHEN Xin MENG FanChao CHEN Run SUN FengBo WANG CunYu GENG Lin school of Materials science and Engineering Harbin Institute of TechnologyHarbin 150001China Waikato Centre for advanced Materials and Manufacturing School of EngineeringUniversity of WaikatoHamilton 3240New Zealand State Key Laboratory of advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

The hot deformation behavior and microstructure evolution of GH3536-TiB2composites fabricated by powder metallurgy(PM)were examined in the temperature range of 950–1150℃ and strain rate range of 0.001–1 s^(-1). The hot compression stress-strain curves and the constitutive equation were obtained. In addition, the hot processing map was drawn, which indicated that the appropriate hot working window was 950–1050℃/0.001–0.1 s^(-1)and 1050–1100℃/0.001–0.01 s^(-1). The microstructure analysis showed that the splitting and spheroidization of M3B2led to a decrease in size and volume fraction at 950–1100℃. At 1150℃,the eutectic microstructure of M_(3)B_(2)+ γ was formed due to the dissolution of M_(3)B_(2), which caused macroscopic cracking of the deformed sample. Additionally, the deformation temperature and the strain rate had little effect on the size and volume fraction of M_(3)B_(2). Besides, discontinuous dynamic recrystallization(DDRX) and continuous dynamic recrystallization(CDRX) were found in the deformed microstructure, while the former was dominant. Within the test range of this work, the dynamic recrystallization(DRX) fraction of the deformed composites was high due to the bulging nucleation of numerous interfaces. The DRX grain size increased with increasing deformation temperature or decreasing strain rate. Texture analysis showed that the deformation texture of //compression direction RD existed in the matrix when the deformation temperature was below 1100℃, and the texture type became //RD at 1100℃. Additionally, it was also found that the //RD texture was formed in M3B2under the strain rates of 0.1 and 0.01 s^(-1).

关键词： GH3536 alloy matrix composites powder metallurgy hot deformation behavior microstructure evolution

Effects of dimethyl ether and ethanol additions on soot transition in ethylene counterflow diffusion flames

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science China(Technological sciences) 2024年第4期67卷 1094-1112页

作者： GUO LinGe YING YaoYao CHEN Chen ZHAO Xuan LIU Dong MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China advanced Combustion Laboratory School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China

This paper investigates the effect of blending dimethyl ether(DME)and ethanol on the soot transition periods in ethylene counterflow diffusion flames by using a novel optical diagnostic *** soot critical transition point in different conditions is identified experimentally and *** kinds of flames are carried out to gain the soot critical transition point in counterflow diffusion flames by changing oxygen fraction(Xo)and changing volume flow rates of fuel and oxidizer(Qv).The red-green-blue(RGB)ratio method is used to precisely identify the soot critical transition point,and chemical kinetic simulations are performed to analyze the detailed reaction *** results show that compared to the ethylene flame,the soot critical transition point occurs at a higher Xoand a lower Qvwhen DME or ethanol is *** addition of DME and ethanol can inhibit soot formation,due to the degree of soot formation reaction being lower than the degree of the oxidation reaction in the blending flames.

关键词： optical diagnosis sooting tendency counterflow diffusion flame dimethyl ether ethanol

Neural network study of the nuclear ground-state spin distribution within a random interaction ensemble

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Nuclear science and Techniques 2024年第3期35卷 216-227页

作者： Deng Liu Alam Noor A Zhen-Zhen Qin Yang Lei school of Mathematics and Physics Southwest University of Science and TechnologyMianyang 621010China school of Nuclear science and technology Southwest University of Science and TechnologyMianyang 621010China

The distribution of the nuclear ground-state spin in a two-body random ensemble(TBRE)was studied using a general classification neural network(NN)model with two-body interaction matrix elements as input features and the corresponding ground-state spins as labels or output *** quantum many-body system problem exceeds the capability of our optimized NNs in terms of accurately predicting the ground-state spin of each sample within the ***,our NN model effectively captured the statistical properties of the ground-state spin because it learned the empirical regularity of the ground-state spin distribution in TBRE,as discovered by physicists.

关键词： Neural network Two-body random ensemble Spin distribution of nuclear ground state

Sensitivity analysis of modeling parameters to soot and PAHs prediction in ethylene inverse diffusion flame

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science China(Technological sciences) 2024年第2期67卷 486-498页

作者： WU BingKun LI TianJiao LIU Dong MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Energy and Power EngineeringNanjing University of Science and TechnologyNanjing 210094China advanced Combustion Laboratory School of Energy and Power EngineeringNanjing University of Science and Technology Nanjing 210094China

The soot formation model based on inverse ethylene diffusion flames was performed to study the sensitivity of the soot formation process to the prediction *** effects of efficiency parameters such as soot inception,surface growth and coagulation on the simulation results were studied by using the adjustable efficiency *** addition,the reversible soot model and conjugate heat transfer(CHT)model were also introduced to explore their *** indicated that,among adjustable efficiency parameters,the nucleation efficiency had the greatest influence on the predicted soot and PAHs distributions,while the Habstraction-C2H2-addition(HACA)process and PAH adsorption surface growth efficiencies impacted *** adjustable efficiency parameters had a significant effect on the concentration of soot gaseous precursors and soot particles,but their effects on temperature,gas phase molecules,and intermediate species were not *** the nucleation efficiency increased from 2×10^(-6)to 1×10^(-4),the predicted value of the integrated soot was increased by nearly 50%,and the maximum primary particle number density and the number of aggregates were increased by an order of *** maximum concentration of BAPYR was ***,the peak temperature along the axial direction increased by only 3.5 *** the reversible soot model,the approximation results of the adjustable efficiency parameters could be modified,which showed the feasibility of the *** use of the CHT model promoted pyrolysis of the fuel below the outlet of the fuel tube,with high-temperature zones,soot zones,and PAHs zones moving towards higher flame ***,when using the reversible model and the CHT model,the maximum soot volume fraction decreased by 39%compared with the basic efficiency parameters,while the concentration of BAPYR increased by 162%,and the concentrations of gas phase species were decreased.

关键词： inverse diffusion flames soot formation soot model ethylene

Age-of-Information-Aware Federated Learning

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Journal of Computer science & technology 2024年第3期39卷 637-653页

作者：徐殷肖明军吴晨吴杰周津锐孙贺 Student Member CCF 1.School of Computer Science and TechnologyUniversity of Science and Technology of ChinaHefei 230026China Suzhou Institute for advanced Research University of Science and Technology of ChinaSuzhou 215123China school of Data science University of Science and Technology of ChinaHefei 230026China Department of Computer and Information sciences Temple UniversityPhiladelphiaPA 19122U.S.A. CCF IEEE

Federated learning(FL)is an emerging privacy-preserving distributed computing paradigm,enabling numerous clients to collaboratively train machine learning models without the necessity of transmitting clients’private datasets to the central *** most existing research where the local datasets of clients are assumed to be unchanged over time throughout the whole FL process,our study addresses such scenarios in this paper where clients’datasets need to be updated periodically,and the server can incentivize clients to employ as fresh as possible datasets for local model *** primary objective is to design a client selection strategy to minimize the loss of the global model for FL loss within a constrained *** this end,we introduce the concept of“Age of Information”(AoI)to quantitatively assess the freshness of local datasets and conduct a theoretical analysis of the convergence bound in our AoI-aware FL *** on the convergence bound,we further formulate our problem as a restless multi-armed bandit(RMAB)***,we relax the RMAB problem and apply the Lagrangian Dual approach to decouple it into multiple ***,we propose a Whittle’s Index Based Client Selection(WICS)algorithm to determine the set of selected *** addition,comprehensive simulations substantiate that the proposed algorithm can effectively reduce training loss and enhance the learning accuracy compared with some state-of-the-art methods.

关键词： federated learning Age of Information restless multi-armed bandit Whittle’s index

Developing an atmospheric aging evaluation model of acrylic coatings:A semi-supervised machine learning algorithm

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International Journal of Minerals,Metallurgy and Materials 2024年第7期31卷 1617-1627页

作者： Yiran Li Zhongheng Fu Xiangyang Yu Zhihui Jin Haiyan Gong Lingwei Ma Xiaogang Li Dawei Zhang Beijing advanced Innovation Center for Materials Genome Engineering Institute for Advanced Materials and TechnologyUniversity of Science and Technology BeijingBeijing 100083China National Materials Corrosion and Protection Data Center University of Science and Technology BeijingBeijing 100083China BRI Southeast Asia Network for Corrosion and Protection(MOE) Shunde Innovation School of University of Science and Technology BeijingFoshan 528399China

To study the atmospheric aging of acrylic coatings,a two-year aging exposure experiment was conducted in 13 representative climatic environments in *** atmospheric aging evaluation model of acrylic coatings was developed based on aging data including11 environmental factors from 567 cities.A hybrid method of random forest and Spearman correlation analysis was used to reduce the redundancy and multicollinearity of the data set by dimensionality reduction.A semi-supervised collaborative trained regression model was developed with the environmental factors as input and the low-frequency impedance modulus values of the electrochemical impedance spectra of acrylic coatings in 3.5wt%NaCl solution as *** model improves accuracy compared to supervised learning algorithms model(support vector machines model).The model provides a new method for the rapid evaluation of the aging performance of acrylic coatings,and may also serve as a reference to evaluate the aging performance of other organic coatings.

关键词： acrylic coatings coatings aging atmospheric environment machine learning