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Navigation Finsler metrics on a gradient Ricci soliton

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Applied Mathematics(A Journal of Chinese Universities) 2024年第2期39卷 266-275页

作者： LI Ying mo Xiao-huan WANG Xiao-yang Department of Applied Mathematics Zhejiang University of TechnologyHangzhou 310023China Key Laboratory of Pure and Applied Mathematics School of Mathematical SciencesPeking UniversityBeijing 100871China School of Mathematics and Statistics Beijing Institute of TechnologyBeijing 100081China

In this paper,we study a class of Finsler metrics defined by a vector field on a gradient Ricci *** obtain a necessary and sufficient condition for these Finsler metrics on a compact gradient Ricci soliton to be of isotropic S-curvature by establishing a new integral *** we determine the Ricci curvature of navigation Finsler metrics of isotropic S-curvature on a gradient Ricci soliton generalizing result only known in the case when such soliton is of Einstein *** its application,we obtain the Ricci curvature of all navigation Finsler metrics of isotropic S-curvature on Gaussian shrinking soliton.

关键词： gradient Ricci soliton navigation Finsler metric isotropic S-curvature Ricci curvature Gaussian shrinking soliton

Giant low-field reversible magnetocaloric effect at liquid helium temperature of niobium and iron co-substituted EuTiO_(3) compounds

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Journal of Rare Earths 2024年第4期42卷 710-715页

作者： Zhihong Hao Quanyi Liu Huicai Xie Yan Zhang Zhaojun mo School of Rare Earth and New Materials Engineering Ganzhou Innovation Center of Rare Earth Permanent Magnet Material Advanced Manufacturing and Intelligent Equipment TechnologyGannan University of Science and TechnologyGanzhou341000China Ganjiang Innovation Academy Chinese Academy of SciencesGanzhou34119China School of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan030024China

Giant magnetocaloric effect(MCE)materials in the liquid helium temperature region have attracted a lot of attention in the field of low-temperature magnetic refrigeration(MR).In this study,a series of niobium(Nb)and iron(Fe)co-substituted EuTiO_(3) perovskites with cubic structure(space group pm3m)was successfully fabricated,and their magnetic properties as well as cryogenic magnetocaloric effects were investigated in *** expected,the introduction of Nb and Fe can significantly modulate the magnetic phase transition and magnetocaloric effect of the EuTiO_(3) *** increasing Fe concentration,two local minima corresponding to the AFM-FM magnetic phase transition near 5.0 K and FM-PM transition near 10 K with no hysteresis in the thermomagnetic curves are observed,which is attributed to an enhancement of FM *** the same time,the gradually widened-ΔSM-T curves and the two peaks with a broad shoulder lead to considerable refrigeration capacity(RC).With the field change ofΔH=2 T,the calculated values of-ΔS_(M)^(max) for the EuTi_(0.9375-x)Nb_(0.0625)Fe_(x)O_(3)(x=0.075,0.1,0.125,0.15)compounds are 24.2,17.6,14.5 and 14.0 J/(kg·K),*** corresponding RC values were calculated to be 144.6,138.3,151.2 and 159 J/kg,***,the values of-ΔS_(M)^(max) for EuTi_(0.8625)Nb_(0.0625)Fe_(0.075)O_(3) are 8.6 and 15.1 J/(kg·K)under low field changes of 0.5 and 1 T,*** giant low-field reversible magnetocaloric effect makes them attractive candidates for magnetic refrigeration in the liquid helium temperature region.

关键词： Magnetocaloric effect Refrigeration capacity Magnetic entropy change Rareearths

Prediction and validation of diffusive uptake rates for indoor volatile organic compounds in axial passive samplers

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Energy and Built Environment 2024年第1期5卷 24-31页

作者： Yan Wang Tao Yu Jinhan mo Department of Building Science Tsinghua UniversityBeijing 100084China Beijing Key Laboratory of Indoor Air Quality Evaluation and Control Beijing 100084China Wuhan Second Ship Design and Research Institute Wuhan 430205China School of Energy and Power Engineering Beihang UniversityBeijing 100191China Key Laboratory of Eco Planning&Green Building Ministry of Education(Tsinghua University)Beijing 100084China

The diffusive uptake rate is essential for using passive samplers to measure indoor volatile organic compounds(VOCs).The traditional theoretical model of passive samplers requires available regression formulas of uptake rates and physicochemical properties of adsorbents to predict the uptake ***,it is difficult to obtain the uptake rates of different VOCs under different sampling periods,and it is also difficult to obtain the physical parameters of adsorbents accurately and *** study provides a reliable numerical prediction method of diffusive uptake rates of *** modeling was based on the standard automated thermal desorption(ATD)tubes packed with Tenax TA and the mass transfer process during *** experimental determinations of toluene uptake rate are carried out to verify the prediction *** uptake rates of typical indoor VOCs are obtained from the literature to calibrate the key apparent parameters in the model by statistical regression *** predicted model can provide the VOC diffusive uptake rates under different sampling duration with an average deviation of less than 5%.This study can provide the basis for fast and accurate prediction of diffusive uptake rates for various VOC pollutants in built environments.

关键词： Indoor air quality Diffusive uptake rate Prediction model Sampling Adsorption

modification of solid electrolyte interface layer between PVDF-based electrolyte and lithium anode

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Journal of Materiomics 2024年第4期10卷 880-888页

作者： Ying Liang Jie Zhang Shundong Guan Kaihua Wen Chuangjie guo Yu-Hsien Wu Haocheng Yuan Sijie Liu Ying Qi Wenbin mo Xue Zhang Ce-Wen Nan State Key Laboratory of New Ceramics and Fine Processing School of Materials Science and EngineeringTsinghua UniversityBeijing100084China Qingtao Institute of New Energy Materials Qingtao(Kunshan)Energy Development Co.LtdKunshanJiangsu215300China

Poly(vinylidene fluoride)(PVDF)-based polymer electrolytes(PEs)with good electrochemical performance and processability as well as low-cost advantage,have great potential applications in solid-state lithium(Li)metal batteries(SSLMBs).PVDF-based PEs are generally produced by employing a solution-casting approach with N,N-dimethylformamide(DMF)as the solvent,accompanied by the formation of[DMF-Li^(+)]complex,which facilitates the Li-ion ***,the residual DMF can react continuously with lithium(Li)metal,thereby deteriorating the interface layer in the middle of the PVDF-based PEs and Li ***,we introduce propylene carbonate(PC)into the PVDF-based PEs to regulate the solvation structure and stabilize the interface layer between the PEs and Li *** accelerates the dissociation of lithium oxalyldifluoroborate(LiODFB).Consequently,“lithium propylene dicarbonate(LPDC)‒B-O”oligomer forms as the interfacial layer with high tenacity,homogeneity,and densification,which improves the interfacial contact and suppresses the continuous reaction between the residual DMF and Li *** further demonstrate that the PVDF-based PE prepared with DMF-PC mix-solvents shows improved room-temperature ionic conductivity(1.18×10^(-3) S/cm),enhanced stability against electrodes,and superior cycling performance in LiCoO_(2)-based SSLMBs(maintaining 84% of the initial discharge capacity after 300 cycles).

关键词： Solid-state battery Lithium metal Poly(vinylidene fluoride)electrolyte Propylene carbonate SEI layer

Recent Advances of Imide-Functionalized Polymer Donors for Non-fullerene Solar Cells

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Chinese Journal of Chemistry 2024年第15期42卷 1759-1780页

作者： Huijuan Wang Songmin mo Dongyan Li Qinghe Wu Department of Chemistry and Key(Guangdong-Hong Kong Joint)Laboratory for Preparation and Application of Ordered Structural Materials of Guangdong Shantou UniversityShantouGuangdong 515063China

In recent years,there has been a shift towards using non-fullerene electron acceptors in organic solar cells(osCs)as a replacement for fullerene *** change requires polymer donors that possess compatible physical properties,such as absorption range,Homo energy level,miscibility,and ***,the high cost and poor batch-to-batch reproducibility of polymer donors also hinder future large-scale *** emphasize the need to explore alternative types of polymer *** imide-functionalized building units possess several key attributes that make their polymers highly promising for non-fullerene *** attributes include ease of synthesis,strong electron-withdrawing ability,rigid and co-planar structure,and the ability to easily tune solubility through imide side *** this review,we summarized the synthetic routes of imide building units,and the structural evolution of imide-functionalized polymer donors by focusing on the effects of polymer structure on their physical,optoelectronic,and photovoltaic *** hope that this mini-review will serve as a catalyst for future research on imide-functionalized polymers toward high-performance,cost-effective,and durable organic solar cells(oscs).

关键词： Imide Polymer donors Organic solar cells Synthetic routes Polymer structure evolution

A high aspect ratio surface micromachined accelerometer based on a SiC-CNT composite material

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Microsystems & Nanoengineering 2024年第2期10卷 219-230页

作者： Jiarui mo Shreyas Shankar Roberto Pezone guoqi Zhang Sten Vollebregt Laboratory of Electronic Components Technology and Materials(ECTM)Department of MicroelectronicsDelft University of TechnologyDelftThe Netherlands

Silicon carbide(SiC)is recognized as an excellent material for microelectromechanical systems(MEMS),especially those operating in challenging environments,such as high temperature,high radiation,and corrosive ***,SiC bulk micromachining is still a challenge,which hinders the development of complex SiC *** address this problem,we present the use of a carbon nanotube(CNT)array coated with amorphous SiC(a-SiC)as an alternative composite material to enable high aspect ratio(HAR)surface *** using a prepatterned catalyst layer,a HAR CNT array can be grown as a structural template and then densified by uniformly filling the CNT bundle with LPCVD *** electrical properties of the resulting SiC-CNT composite were characterized,and the results indicated that the electrical resistivity was dominated by the *** demonstrate the use of this composite in MEMS applications,a capacitive accelerometer was designed,fabricated,and *** fabrication results showed that the composite is fully compatible with the manufacturing of surface micromachining *** Young’s modulus of the composite was extracted from the measured spring constant,and the results show a great improvement in the mechanical properties of the CNTs after coating with *** accelerometer was electrically characterized,and its functionality was confirmed using a mechanical shaker.

关键词： composite surface electrical

Dynamic recrystallization behavior and strengthening mechanism of a novel mo-Ti_(3)AlC_(2) alloy at ultrahigh temperature

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Rare Metals 2024年第8期43卷 3946-3960页

作者： Lu Yang xin-Yuan Zheng Yang Zhao Xi-Ran Wang Fang-Nao Xiao Shi-Zhong Wei School of Materials Science and Engineering Henan University of Science and TechnologyLuoyang 471023China National Joint Engineering Research Center for Abrasion Control and molding of Metal Materials Henan University of Science and TechnologyLuoyang 471003China Department of Applied Mechanics Univ.Bourgogne FrancheComteFEMTO-ST InstituteCNRS/UF/ENSMM/UTBM25000BesangonFrance

Increasing the recrystallization temperature to achieve better high-temperature performance is critical in the development of molybdenum alloys for ultrahightemperature applications,such as the newest generation of multitype high-temperature nuclear *** this study,an innovative strategy was proposed to improve the performance of molybdenum alloys at high temperature by using the two-dimensional MAX(where M is an early transition metal,A is an A-group element and X is C or N)ceramic material Ti_(3)AlC_(2).The relationships between flow stress,strain rate and temperature were *** microstructure,distribution of misorientation and evolution of dislocations in the mo-Ti_(3)AlC_(2) alloy were *** microscopic mechanism of the Ti_(3)AlC_(2) phase in the molybdenum alloy at high temperatures was *** experimental results showed that the peak flow stress of mo-Ti_(3)AlC_(2) at 1600℃ reached 155 MPa,which was161.8% greater than that of pure *** activation energy of thermal deformation of mo-Ti_(3)AlC_(2) was as large as537 kJ·mol~(-1),which was 17.6% more than that of pure *** recrystallization temperature reached 1600℃ or even *** topological reaction of the Ti_(3)AlC_(2) phase consumed a large amount of energy at high temperatures,resulting in increases in the deformation activation *** structures of AlTi_3 and Ti-O Magneli-phase oxides(Ti_nO_(2n-1)) were formed in-situ,which relied on kink bands and interlayer slip,resulting in many dislocations during ***,the special two-dimensional of the structure Ti_(3)AlC_(2) ceramic inhibited the recrystallization behavior of the mo *** results of this study can provide theoretical guidance for the development of a new generation of molybdenum alloys for use in ultrahigh-temperature environments.

关键词： mo alloy Two-dimensional reinforcement Dynamic recrystallization behavior Hot deformation Mechanical properties

From atomistic modeling to materials design:computation-driven material development in lithium-ion batteries

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Science China Chemistry 2024年第1期67卷 276-290页

作者： Xiangrong Li Xiang Chen Qiang Bai Yifei mo Yizhou Zhu Research Center for Industries of the Future and School of Engineering Westlake UniversityHangzhou 310030China Department of Chemical Engineering Tsinghua UniversityBeijing 100084China College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Department of Materials Science and Engineering University of MarylandCollege Park 20742United States

As an advanced energy storage system,lithium-ion batteries play an essential role in modern *** their ubiquitous success,there is a great demand for continuous improvements of the battery performance,including higher energy density,lower safety risk,longer cycling life,and lower *** performance improvement requires the design and development of novel electrode and electrolyte materials that exhibit desirable properties and satisfy strict *** modeling can provide a unique perspective to fundamentally understand and rationally design battery *** this paper,we review a few recent successful examples of computation-driven discovery and design in electrode and electrolyte ***,we highlight how atomistic modeling can reveal the underlying mechanisms,predict the important properties,and guide the design and engineering of electrode and electrolyte *** have a conclusion with a discussion of the unique capability of atomistic modeling in battery material development and provide a perspective on future challenges and directions for computation-driven battery material developments.

关键词： materials design computation modeling batteries electrolyte electrode

morphology Study for GeV Emission of Nearby Supernova Remnant G332.5-5.6

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Research in Astronomy and Astrophysics 2024年第4期24卷 134-140页

作者： Ming-Hong Luo Qing-Wen Tang Xiu-Rong mo Department of Physics School of Physics and Materials ScienceNanchang UniversityNanchang 330031China

A spatial template is important to study nearby supernova remnants(SNRs).For SNR G332.5-5.6,we report a Gaussian disk with a radius of about 1°.06 to be a potential good spatial model in the γ-ray *** this new Gaussian disk,its GeV lightcurve shows a significant variability of about seven *** γ-ray observations of this SNR could be explained well either by a leptonic model or a hadronic model,in which a flat spectrum for the ejected electrons/protons is required.

关键词： ISM:supernova remnants gamma rays:ISM