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macro-architectured cellular materials： Properties, characteristic modes, and prediction methods

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Frontiers of Mechanical Engineering 2018年第3期13卷 442-459页

作者： Zheng-dong ma The University of Michigan Ann Arbor MI 48109 USA

macro-architectured cellular （maC） material is defined as a class of engineered materials having configurable cells of relatively large （i.e., visible） size that can be architecturally designed to achieve various desired material properties. Two types of novel maC materials, negative Poisson＇s ratio material and biomimetic tendon reinforced material, were introduced in this study. To estimate the effective material properties for structural analyses and to optimally design such materials, a set of suitable homogenization methods was developed that provided an effective means for the multiscale modeling of maC materials. First, a strain-based homogenization method was developed using an approach that separated the strain field into a homogenized strain field and a strain variation field in the local cellular domain superposed on the homogenized strain field. The principle of virtual displacements for the relationship between the strain variation field and the homogenized strain field was then used to condense the strain variation field onto the homogenized strain field. The new method was then extended to a stress-based homogenization process based on the principle of virtual forces and further applied to address the discrete systems represented by the beam or frame structures of the aforementioned maC materials. The characteristic modes and the stress recovery process used to predict the stress distribution inside the cellular domain and thus determine the material strengths and failures at the local level are also discussed.

关键词： architectured material cellular materials multi-scale modeling homogenization method effective material properties computational method

Interactions between long interpregnancy interval and advanced maternal age on neonatal outcomes

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World Journal of Pediatrics 2023年第12期19卷 1155-1161页

作者： Yan ma hua Fu Yang li Zheng‑Rong Bao Wen‑Bin dong Xiao‑Ping Lei Division of Neonatology Department of PediatricsThe Affiliated Hospital of Southwest Medical UniversityXiaoping Lei8 Kangcheng RoadLuzhou 646000China Department of Perinatology The Afliated Hospital of Southwest Medical UniversityLuzhouChina Sichuan Clinical Research Center for Birth Defects LuzhouChina School of Pediatrics Southwest Medical UniversityLuzhouChina

Background After the implementation of the universal two-child policy in China,it was more frequent to have long interpregnancy intervals(IPIs)and advanced maternal ***,the interactions between long IPIs and advanced maternal age on neonatal outcomes are *** The study subjects of this historical cohort study were multiparas with singleton live births between October 1st,2015,and October 31st,*** was defned as the interval between delivery and conception of the subsequent *** regression models were used to calculate adjusted odds ratios(aORs)and 95%confdence intervals(CIs)of the risks of preterm birth(PTB),low birth weight(LBW),small for gestation age,and 1-min Apgar score≤7 in diferent IPI *** excess risk due to interaction(RERI)was used to evaluate the additive interaction between long IPIs and advanced maternal *** Compared with the 24≤IPI≤59 months group,the long IPI group(IPI≥60 months)was associated with a higher risk of PTB(aOR,1.27;95%CI:1.07–1.50),LBW(aOR,1.32;95%CI 1.08–1.61),and one-minute Apgar score≤7(aOR,1.46;95%CI 1.07–1.98).Negative additive interactions(all RERIsmaternal age for these neonatal ***,IPImaternal age and to improve neonatal outcomes.

关键词： Interaction Interpregnancy interval Low birth weight maternal age Preterm birth

Protection Methods to Reduce Nitrogen and Phosphorus Losses from Sloping Citrus Land in the Three Gorges Area of China

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Pedosphere 2015年第3期25卷 478-488页

作者： XIA Li-Zhong LIU Guo-hua WU Yong-Hong ma Li LI Yun-dong Institute of Soil Science Chinese Academy of Sciences

The increased application of chemical fertilizers in citrus orchards and the non-point source nitrogen(N) and phosphorus(P)diffusion threaten the fresh water quality of the Three Gorges Reservoir area of China. A 10-year field trial on sloping citrus lands was conducted to evaluate five protection methods for reducing N and P losses: 1) intercropping with perennial white clover(CW); 2) straw mulching of the soil surface(CS); 3) intercropping with yellow daylily contour hedgerows(CH); 4) an impermeable membrane buried in the soil along the contour lines(CM); and 5) intercropping with a rotation of wheat and peanut(CWP). An area of conventional citrus management was also maintained as the control(CK). The results showed that CM and CH were the most effective methods for reducing surface runoff. The sediment yield were reduced at the highest rate by CW and CH and was also significantly reduced by CS. Reduced runoff volume and sediment yield were the crucial mechanism for the reductions in N and P losses. Compared with the control, CW, CS, CH, and CM reduced annual runoff by 9%, 13%, 25%, and 30%, sediment yield by 77%, 55%, 71%, and 28%,N loss by 10%, 23% 36%, and 37%, and P loss by 39%, 31%, 27%, and 25%, respectively. CW, CS, CH, and CM were effective in reducing N and P losses from the sloping citrus land. However, over the long-term, surface soil nutrient accumulation in CW, CS, and CH diminished the benefit of those methods in reducing N and P losses. In addition, CWP increased soil erosion and nutrient loss,which showed that citrus intercropping with other crops was an unsuitable method for citrus sloping land in the Three Gorges area.

关键词： contour hedgerows impermeable membrane intercropping runoff sediment straw mulching

Large aperture phase-coded diffractive lens for achromatic and 16°field-of-view imaging with high efficiency

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Chinese Physics B 2022年第7期31卷 349-360页

作者： Gu ma Peng-Lei Zheng Zheng-Wen Hu Suo-dong ma Feng Xu dong-Lin Pu Qin-hua Wang School of Optoelectronic Science and Engineering and Collaborative Innovation Center of Suzhou Nano Science and Technology Soochow UniversitySuzhou 215006China Key Laboratory of Advanced Optical manufacturing Technologies of Jiangsu Province and Key Laboratory of Modern Optical Technologies of Education Ministry of China Soochow UniversitySuzhou 215006China CAS Key Laboratory of Space Precision Measurement Technology Xi’an 710119China

Diffractive lenses(DLs)can realize high-resolution imaging with light weight and compact *** DLs suffer large chromatic and off-axis aberrations,which significantly limits their practical *** many achromatic methods have been proposed,most of them are used for designing small aperture DLs,which have low diffraction *** the designing of diffractive achromatic lenses,increasing the aperture and improving the diffraction efficiency have become two of the most important design ***,a novel phase-coded diffractive lens(PCDL)for achromatic imaging with a large aperture and high efficiency is proposed and demonstrated experimentally,and it also possesses wide field-of-view(FOV)imaging at the same *** phase distribution of the conventional phase-type diffractive lens(DL)is coded with a cubic function to expand both the working bandwidth and the FOV of conventional *** proposed phase-type DL is fabricated by using the laser direct writing of grey-scale patterns for a PCDL of a diameter of 10 mm,a focal length of 100 mm,and a cubic phase coding parameter of 30π.Experimental results show that the working bandwidth and the FOV of the PCDL respectively reach 50 nm and 16°with over 8%focusing efficiency,which are in significant contrast to the counterparts of conventional DL and in good agreement with the theoretical *** work provides a novel way for implementing the achromatic,wide FOV,and high-efficiency imaging with large aperture DL.

关键词： achromatic imaging diffractive lens phase coding large aperture high efficiency

Deciphering the role of ultra-low-loaded rhodium in NiFe-MIL-53 for superior oxygen evolution reaction

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Journal of Energy Chemistry 2025年第1期100卷 77-86页

作者： Jinzhi Jia Jinhua Zhang Kailu Guo Lanyue Zhang Gening Du Hao You Junfeng huang Mudong Tu hua Li Yong Peng Wei Dou Cailing Xu State Key Laboratory of Applied Organic Chemistry College of Chemistry and Chemical Engineering School of Materials and Energy Lanzhou University College of Chemistry and Chemical Engineering Luoyang Normal University

Designing highly active and stable electrocatalysts of oxygen evolution reaction （OER） is one of the crucial *** this study,a novel OER electrocatalyst,NiFe-MIL-53 modified with ultra-low rhodium（Rh@NiFe-MIL-53）,is successfully prepared via the hydrothermal ***-situ Raman spectroscopy and electrochemical impedance spectroscopy reveal that the doped Rh accelerates the phase transformation of NiFe-MIL-53 and the in-situ formed Rh@NiFeOOH is the actual active *** importantly,the enhanced reversibility of electrochemical reconstruction between NiFeOOH and NiFe（OH）2after doping Rh is beneficial for improving the electrochemical stability of the catalyst.X-ray photoelectron spectroscopy spectra show the strong electronic interaction between single-atom Rh and Ni/Fe in Rh@***,theoretical calculations confirm that the integration of single-atom Rh into the NiFeOOH successfully reduces the band gap,regulates the d-band center （εd）,accelerates the charge transfer,and optimizes the adsorption behavior of oxygen-containing intermediates,thereby lowering the energy barrier of rate-determining ***,the optimized Rh@NiFe-MIL-53 exhibits excellent OER activity （240 mV） with a small Tafel slope of 48.2 mV dec-1and long-term durability (over1270 h at 10 m A cm-2and 110 h at 200 ma cm-2).This work presents a new perspective on designing highly efficient OER electrocatalysts.

关键词： NiFe-MIL-53 Rh Electrochemical reconstruction Catalytic mechanism Oxygen evolution reaction

Capture and detumbling control for active debris removal by a dual-arm space robot

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Chinese Journal of Aeronautics 2022年第9期35卷 342-353页

作者： dong HAN Gangqi dong Panfeng huaNG Zhiqing ma National Key Laboratory of Aerospace Flight Dynamics Northwestern Polytechnical UniversityXi'an 710072China Research Center for Intelligent Robotics School of AstronauticsNorthwestern Polytechnical UniversityXi'an 710072China

Active debris removal(ADR) technology is an effective approach to remediate the proliferation of space debris, which seriously threatens the operational safety of orbital spacecraft. This study aims to design a controller for a dual-arm space robot to capture tumbling debris, including capture control and detumbling control. Typical space debris is considered as a non-cooperative target, which has no specific capture points and unknown dynamic parameters. Compliant clamping control and the adaptive backstepping-based prescribed trajectory tracking control(PTTC)method are proposed in this paper. First, the differential geometry theory is utilized to establish the constraint equations, the dynamic model of the chaser-target system is obtained by applying the Hamilton variational principle, and the compliance clamping controller is further designed to capture the non-cooperative target without contact force feedback. Next, in the post-capture phase,an adaptive backstepping-based PTTC is proposed to detumble the combined spacecraft in the presence of model uncertainties. Finally, numerical simulations are carried out to validate the feasibility of the proposed capture and detumbling control method. Simulation results indicate that the target detumbling achieved by the PTTC method can reduce propellant consumption by up to24.11%.

关键词： Active debris removal Adaptive backstepping control Compliant clamping control Prescribed trajectory tracking Space robot

Effect of Particle Size on Mechanical Properties and Fracture Behaviors of Age-Hardening SiC/Al–Zn–Mg–Cu Composites

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Acta Metallurgica Sinica(English Letters) 2021年第10期34卷 1447-1459页

作者： Guonan ma dong Wang Bolv Xiao Zongyi ma Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

15 vol.% SiC/Al-6.5Zn-2.8 Mg-1.7 Cu(wt%) composites with varying particle sizes(3.5, 7.0, 14 and 20 μm), i.e., C-3.5, C-7.0, C-14, and C-20, respectively, were fabricated by powder metallurgy(PM) method and subjected to microstructural examination. The effect of particle size on mechanical properties and fracture behaviors of the T6-treated composites was revealed and analyzed in detail. Element distribution and precipitates variations in the composites with varying particle sizes were emphatically considered. Results indicated that both tensile strength and plasticity of the T6-treated composites increased first and then decreased with particle size decreasing. The C-7.0 composite simultaneously exhibited the highest ultimate tensile strength(UTS) of 686 MPa and best elongation(El.) of 3.1%. The smaller-sized SiC particle would introduce more oxide impurities, which would react with the alloying element in the matrix to cause Mg segregation and depletion. According to strengthening mechanism analysis, the weakening of precipitation strengthening in the T6-treated C-3.5 composite was the main cause of the lower tensile strength. Additionally, the larger SiC particle, the more likely to fracture, especially in the composites with high yield strength. For the T6-treated C-20 composites, more than 75% SiC particles were broken up, resulting in the lowest plasticity. As decreasing particle size, the fracture behaviors of the T6-treated composites would change from particle fracture to matrix alloy fracture gradually.

关键词： Metal matrix composites Mechanical properties Particle size Fracture behaviors Strengthening mechanisms

FLOW REGIMES BELOW AERATORS FOR DISCHARGE TUNNELS

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Journal of Hydrodynamics 2012年第3期24卷 378-382页

作者： ma Fei WU Jian-hua College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China

The flow regimes below an aerator influence directly the air entrainment and the cavitation damage control. Based on the theoretical considerations, the experiments of the aerator for a discharge tunnel were conducted, and the relationships between the flow regime and hydraulic and geometric parameters were investigated. The results showed that, there are two kinds of threshold values for the flow regime conversions. One is Fr1-2 standing for the conversion from the fully filled cavity to the partially filled cavity, and the other is Fr2-3 which shows the change from the partially filled cavity to the net air cavity. Two empirical expressions were obtained for the conversions of the flow regimes, which can be used in the designs of the aerators.

关键词： aerator discharge tunnel flow regime filling water jet length

Kernel Least Mean Kurtosis Based Online Chaotic Time Series Prediction

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Chinese Physics Letters 2013年第11期30卷 44-48页

作者： QU hua ma Wen-Tao ZHAO Ji-Hong CHEN Ba-dong School of Electronic and Information Engineering Xi'an Jiaotong UniversityXi'an 710049 School of Telecommunication and Information Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121 Institute of Artificial Intelligence and Robotics Xi'an Jiaotong UniversityXi'an 710049

Based on the kernel methods and the nonlinear feature of chaotic time series,we develop a new algorithm called kernel least mean kurtosis(KLMK)by applying the kernel trick to the least mean kurtosis(LMK)algorithm,which maps the input data to a high dimensional feature *** KLMK algorithm can overcome the shortcomings of the original LMK for nonlinear time series prediction,and it is easy to implement a sample by sample adaptation *** analysis suggests that the KLMK algorithm may converge in a mean square sense in nonlinear chaotic time series prediction under certain *** results show that the performance of KLMK is better than those of LMK and the kernel least mean square(KLMS)algorithm.

关键词： conditions space kernel