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Love wave propagation in one-dimensional piezoelectric quasicrystal multilayered nanoplates with surface effects

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Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 619-632页

作者： xin feng Liaoliang KE Yang GAO College of Science China Agricultural UniversityBeijing 100083China School of Mechanical Engineering Tianjin UniversityTianjin 300350China

The exact solutions for the propagation of Love waves in one-dimensional(1D)hexagonal piezoelectric quasicrystal(PQC)nanoplates with surface effects are *** electro-elastic model is developed to investigate the anti-plane strain problem of Love wave *** introducing three shape functions,the wave equations and electric balance equations are decoupled into three uncorrelated *** the boundary conditions of the top surface on the covering layer,the interlayer interface,and the matrix,a dispersive equation with the influence of multi-physical field coupling is provided.A surface PQC model is developed to investigate the surface effects on the propagation behaviors of Love waves in quasicrystal(QC)multilayered structures with nanoscale thicknesses.A novel dispersion relation for the PQC structure is derived in an explicit closed form according to the non-classical mechanical and electric boundary *** examples are given to reveal the effects of the boundary conditions,stacking sequence,characteristic scale,and phason fluctuation characteristics on the dispersion curves of Love waves propagating in PQC nanoplates with surface effects.

关键词： piezoelectric quasicrystal(PQC)material multilayered plate dispersion characteristic surface effect

Recent advances in heterogeneous hydrosilylation of unsaturated carbon-carbon bonds

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Chinese Chemical Letters 2024年第6期35卷 71-85页

作者： heng Yang Zhijie Zhou Conghui Tang feng Chen School of Chemistry and Chemical Engineering Yangzhou UniversityYangzhou 225002China Key Laboratory of Material Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Material Chemistry and Service FailureSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan 430074China

The hydrosilylation of unsaturated carbon-carbon bonds is one of the most critical reactions in silicone industrial *** homogeneous Speier's catalyst,Karstedt's catalyst,and other noble metal-based catalysts are widely ***,simplifying the separation of the homogeneous catalyst from reaction products and reducing the high cost of precious metals is still *** review describes the recent development of heterogeneous catalysts for alkene,alkyne,and allene hydrosilylations,which can effectively solve problems in homogeneous hydrosilylation.

关键词： Hydrosilylation Heterogeneous catalysis Alkenes Alkynes Silanes

Excitation-Contraction Coupling Time is More Sensitive in Evaluating Cardiac Systolic Function

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Chinese Medical Journal 2018年第15期131卷 1834-1839页

作者： Juan Gao Min Zhu Hai-Yi Yu Shi-Qiang Wang xin-heng feng Ming Xu Department of Cardiology and Institute of Vascular Medicine Peking University Third Hospital Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides Ministry of Health Key Laboratory of Molecular Cardiovascular Science Ministry of Education Beijing Key Laboratory of Cardiovascular Receptors Research Beijing 100191 China State Key Laboratory of Membrane Biology College of Life Sciences Peking University Beijing 100871 China

Background： Pressure overload-induced myocardial hypertrophy is a key step leading to heart failure. Previous cellular and animal studies demonstrated that deteriorated excitation-contraction coupling occurs as early as the compensated stage of hypertrophy before the global decrease in left ventricular ejection fraction （LVEF）. This study was to evaluate the cardiac electromechanical coupling time in evaluating cardiac systolic function in the early stage of heart failure. Methods： Twenty-six patients with Stage B heart failure （SBHF） and 31 healthy controls （CONs） were enrolled in this study. M-mode echocardiography was performed to measure LVEF. Tissue Doppler imaging （TDI） combined with electrocardiography （ECG） was used to measure cardiac electromechanical coupling time. Results： There was no significant difference in LVEF between SBHF patients and CONs （64.23 ± 8.91% vs. 64.52 ± 5.90%; P= 0.886）. However, all four electromechanical coupling time courses （Qsb： onset of Q wave on ECG to beginning of S wave on TDI, Qst： onset of Q wave on ECG to top of S wave on TDI, Rsb： top of R wave on ECG to beginning orS wave on TDI, and Rst： top of R wave on ECG to top orS wave on TDI） of SBHF patients were significantly longer than those of CONs （Qsb： 119.19 ± 35.68 ms vs. 80.30 ± 14.81 ms, P 〈 0.001 ; Qst： 165.42 ± 60.93 ms vs. 129.04 ± 16.97 ms, P = 0.006; Rsb： 82.43 ± 33.66 ms vs. 48.30 ± 15.18 ms, P 〈 0.001; and Rst： 122.37 ± 36.66 ins vs. 93.25 ± 16.72 ms, P = 0.001 ）, and the Qsb, Rsb, and Rst time showed a significantly higher sensitivity than LVEF （Rst： P =0.032; Rsb： P = 0.003; and Qsb： P = 0.004）. Conclusions： The cardiac electromechanical coupling time is more sensitive than LVEF in evaluating cardiac systolic function.

关键词： Excitation-Contraction Couplings Heart Failure Left Ventricular Dysfunction

Amorphous Sb/C composite with isotropic expansion property as an ultra-stable and high-rate anode for lithium-ion batteries

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Rare Metals 2024年第5期43卷 2039-2052页

作者： Ze-Zhou Yang Cheng-Yi Zhang Yu-Qing Ou Zhi-Kang Su Yan Zhao heng-Jiang Cong xin-Ping Ai Jiang-feng Qian Hubei Key Laboratory of Electrochemical Power Sources College of Chemistry and Molecular SciencesWuhan UniversityWuhan430072China Institute of Technological Sciences Wuhan UniversityWuhan 430072China

Antimony(Sb)is an intriguing anode material for Li-ion batteries(LIBs)owing to its high theoretical capacity of 660 m Ah·g^(-1)and appropriate working potential of~0.8 V(***^(+)/Li).However,just like all alloying materials,the Sb anode suffers from huge volume expansion(230%)during repeated insertion/extraction of Li+ions,resulting in structural deterioration and rapid capacity *** this work,a novel amorphous Sb/C composite with atomically dispersed Sb particles in carbon matrix is prepared via a straightforward high-energy ball milling *** intimate intermixing of amorphous Sb with C provides homogeneous element distribution and isotropic volume expansion during cycling,resulting in persistent structural ***,the disordered structure of amorphous material shortens the diffusion distance of lithium ions/electrons,promoting fast reaction kinetics and rate *** from the aforementioned effects,the amorphous Sb/C exhibits a high reversible capacity of537.4 m Ah·g^(-1)at 0.1 A·g^(-1)and retains 201.0 m Ah·g^(-1)at an ultrahigh current rate of 10.0 A·g^(-1).Even after 1500deep cycles at 2.0 A·g^(-1),the amorphous Sb/C electrode still maintains 86.3%of its initial capacity,which outperforms all existing Sb-based anodes reported so *** analysis further reveals a greatly reduced volume variation of merely 34.6%for the amorphous Sb/C electrode,much lower than that of 223.1%for crystalline Sb *** study presents a new approach to stabilizing Sb-based alloy anodes and contributes to the construction of high-performance amorphous anode materials for LIBs,enabling advanced energy storage.

关键词： Amorphous Sb/C anode Homogeneous element distribution Isotropic volume expansion Ultra-long cycle stability High-rate capability Lithium-ion battery

Effect of hot isostatic pressure on the microstructure and tensile properties of γ'-strengthened superalloy fabricated through induction-assisted directed energy deposition

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 1089-1097页

作者： Jianjun Xu Hanlin Ding xin Lin feng Liu Analytical&Testing Center Northwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

The microstructure characteristics and strengthening mechanism of Inconel738LC(IN-738LC) alloy prepared by using induction-assisted directed energy deposition(IDED) were elucidated through the investigation of samples subjected to IDED under 1050℃ preheating with and without hot isostatic pressing(HIP,1190℃,105 MPa,and 3 h).Results show that the as-deposited sample mainly consisted of epitaxial columnar crystals and inhomogeneously distributed γ’ phases in interdendritic and dendritic core *** HIP,grain morphology changed negligibly,whereas the size of the γ’ phase became increasingly *** further heat treatment(HT,1070℃,2 h + 845℃,24 h),the γ’ phase in the as-deposited and HIPed samples presented a bimodal size distribution,whereas that in the as-deposited sample showed a size that remained *** comparison of tensile properties revealed that the tensile strength and uniform elongation of the HIP + HTed sample increased by 5% and 46%,respectively,due to the synergistic deformation of bimodal γ’phases,especially large cubic γ’ ***,the relationship between phase transformations and plastic deformations in the IDEDed sample was discussed on the basis of generalized stability theory in terms of the trade-off between thermodynamics and kinetics.

关键词： directed energy deposition Ni-based superalloys high-temperature preheating hot isostatic pressing microstructure tensile properties

Classification and spectrum optimization method of grease based on infrared spectrum

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Friction 2024年第6期12卷 1154-1164页

作者： xin feng Yanqiu XIA Peiyuan XIE Xiaohe LI School of Energy Power and Mechanical Engineering North China Electric Power UniversityBeijing 102206China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

The infrared(IR)absorption spectral data of 63 kinds of lubricating greases containing six different types of thickeners were obtained using the IR *** Kohonen neural network algorithm was used to identify the type of the lubricating *** results show that this machine learning method can effectively eliminate the interference fringes in the IR spectrum,and complete the feature selection and dimensionality reduction of the high-dimensional spectral *** 63 kinds of greases exhibit spatial clustering under certain IR spectrum recognition spectral bands,which are linked to characteristic peaks of lubricating greases and improve the recognition accuracy of these *** model achieved recognition accuracy of 100.00%,96.08%,94.87%,100.00%,and 87.50%for polyurea grease,calcium sulfonate composite grease,aluminum(Al)-based grease,bentonite grease,and lithium-based grease,*** on the different IR absorption spectrum bands produced by each kind of lubricating grease,the three-dimensional spatial distribution map of the lubricating grease drawn also verifies the accuracy of classification while recognizing the *** paper demonstrates fast recognition speed and high accuracy,proving that the Kohonen neural network algorithm has an efficient recognition ability for identifying the types of the lubricating grease.

关键词： grease infrared(IR)spectroscopy layered Kohonen network species recognition spectrum band optimization

Optimal search path planning of UUV in battlefeld ambush scene

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Defence Technology（防务技术） 2024年第2期32卷 541-552页

作者： Wei feng Yan Ma heng Li Haixiao Liu Xiangyao Meng Mo Zhou Naval Research Institute Beijing100161China

Aiming at the practical application of Unmanned Underwater Vehicle(UUV)in underwater combat,this paper proposes a battlefield ambush scene with UUV considering ocean ***,by establishing these mathematical models of ocean current environment,target movement,and sonar detection,the probability calculation methods of single UUV searching target and multiple UUV cooperatively searching target are given ***,based on the Hybrid Quantum-behaved Particle Swarm Optimization(HQPSO)algorithm,the path with the highest target search probability is ***,through simulation calculations,the influence of different UUV parameters and target parameters on the target search probability is analyzed,and the minimum number of UUVs that need to be deployed to complete the ambush task is demonstrated,and the optimal search path scheme is *** method proposed in this paper provides a theoretical basis for the practical application of UUV in the future combat.

关键词： Battlefield ambush Optimal search path planning UUV path Planning Probability of cooperative search

Rapid recovery of desert shrubs is attributed to imbalance of water supply to demand after disturbance in Northwest China

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Ecological Processes 2024年第2期13卷 118-129页

作者： Hai Zhou Xiangyan feng Zhibin He Qiyue Yang heng Ren Wenzhi Zhao Linze Inland River Basin Research Station Chinese Ecosystem Research Network Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences University of Chinese Academy of Sciences

Background Disturbance is a key driver of changes in terrestrial ecosystems, especially in water limited regions. In the desert ecosystem of Northwest China, shrubs are often foraged by camels and this causes the shrubs lost their aboveground tissues. Although the aboveground tissue could recover after the disturbance, the mechanisms of resprouts' recovery after the disturbance are still poorly understood. We investigated the morphological and physiological characteristics and root water uptake sources of resprouts and non-disturbed seedlings of four desert shrub species that were often foraged by *** The results showed that the resprouts grew rapidly after the removal of aboveground tissue. The height and aboveground biomass of resprouts reached the level of 5-year-old seedlings following a growing season. Compared to un-disturbed seedlings, higher leaf water potential, leaf hydraulic conductance and photosynthesis rate were observed in resprouts, indicating that resprouts grew rapidly after disturbance. Furthermore, we found that the root water uptake source did not change after disturbance. This indicated that the roots of resprouts kept intact water uptake capacity after disturbance, which could keep supplying sufficient water to the aboveground tissue. Due to the removal of aboveground tissue of the resprouts, the water demand of aboveground tissue decreased, which induced an imbalance of water supply from roots to demand of aboveground tissues of resprouts. This explained the improved physiological performance and rapid recovery of resprouts after *** The imbalance of water supply to demand contributes to the rapid recovery of desert shrubs after disturbance. The findings provide insight into the eco-physiological mechanism for the maintenance of desert ecosystems that are facing disturbance.

关键词： Disturbance Resprout Physiological performance Shrub Water uptake source

Relationship between exercise induced elevation of left ventricular filling pressure and exercise intolerance in patients with atrial fibrillation

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Journal of Geriatric Cardiology 2016年第6期13卷 546-551页

作者： Shao-Min CHEN Rong HE Wei-Hong LI Zhao-Ping LI Bao-Xia CHEN xin-heng feng Department of Cardiology Peking University Third Hospital Key Laboratory of Cardiovascular Molecular Biology and Regulatory peptides Ministry of Health Beijing China Department of Cardiology Beijing Tsinghua Changgung Hospital Medical Center Tsinghua University Beijing China

Background Elevated left ventricular filling pressure （LVFP） is an important cause of exercise intolerance in patients with atrial fib- dilation （AF）. Exercise stress echocardiography could assess LVFP during exercise. The objective of this study was to investigate the relationship between exercise induced elevation of LVFP and exercise capacity in patients with AF. Methods This study included 145 con- secutive patients （81 men and 64 women; mean age 65.5 ± 8.0 years） with persistent non-valvular AF and normal left ventricular systolic function （left ventdcular ejection fraction 〉 50%）. All patients underwent a symptom-limited cardiopulmonary exercise test （CPET）. Doppler echocardiography was performed both at rest and immediately after exercise. Five consecutive measurements of early diastolic mitral inflow velocity （E） and early diastolic mitral annular velocity （e＇） were taken and averaged. E/e＇ ratio was calculated. Elevated LVFP was defined as E/e＇〉 9, and patients with elevated LVFP at rest were excluded. Results Patients were classified into two groups according to LVFP estimated by E/e＇ ratio after exercise： 39 （26.9%） with elevated LVFP after exercise and 106 （73.1%） with normal LVFP. As compared with patients with normal LVFP, the ones with elevated LVFP after exercise had significantly lower peak oxygen uptake （VO2 peak）（21.7 ± 2.3 vs. 26.4 ± 3.8 mL/min per kilogram, P 〈 0.001）, lower anaerobic threshold （19.9 ± 2.5 vs. 26.0± 4.0 mL/min per kilogram, P 〈 0.001）, and shorter exercise time duration （6.2± 0.8 vs. 7.0 ±1.3 min, P 〈 0.001）. Multivariate analysis showed that age, gender and E/e＇ after exercise were significantly correlated with VO2peak. Conclusion Elevated LVFP estimated by E/e＇ ratio after exercise is independently associated with reduced exercise capacity in AF patients.

关键词： Atrial fibrillation Diastolic dysfunction Exercise capacity, Exercise stress echocardiography