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Thermodynamic limits for simultaneous energy harvesting from the hot sun and cold outer space

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Light(Science & Applications) 2020年第1期9卷 1373-1383页

作者： wei Li Siddharth Buddhiraju Shanhui fan Department of Electrical Engineering Ginzton LaboratoryStanford UniversityStanfordCA 94305USA

The sun and outer space are two of the most important fundamental thermodynamic resources for renewable energy harvesting.A significant amount of work has focused on understanding the fundamental limit of energy harvesting from the *** recently,there have been several theoretical analyses of the fundamental limit of energy harvesting from outer ***,far less is understood about the fundamental limits of simultaneous energy harvesting from both the sun and outer ***,we consider and introduce various schemes that are capable of simultaneous energy harvesting and elucidate the fundamental thermodynamic limits of these *** show that the theoretical limits can far exceed the previously established limit associated with utilizing only one thermodynamic *** results highlight the significant potential of simultaneous energy harvesting and indicate new fundamental opportunities for improving the efficiency of energy harvesting systems.

关键词： outer harvesting simultaneous

Analysis of limit cycle oscillations of a typical airfoil section with freeplay

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Acta Mechanica Sinica 2013年第4期29卷 583-592页

作者： Si-Jin Zhang Gui-Lin Wen fan Peng zi-Qiang Liu School of Mechanical and Vehicle Engineering Hunan University Institute of Astronautic Aero-Dynamics and Technology

A typical airfoil section system with freeplay is investigated in the paper. The classic quasi-steady flow model is applied to calculate the aerodynamics, and a piecewise-stiffness model is adopted to characterize the non- linearity of the airfoil section＇s freeplay. There are two crit- ical speeds in the system, i.e., a lower critical speed, above which the system might generate limit cycle oscillation, and an upper critical one, above which the system will flutter. Then a Poincar6 map is constructed for the limit cycle os- cillations by using piecewise-linear solutions with and with- out contact in the system. Through analysis of the Poincar6 map, a series of equations which can determine the frequen- cies of period-1 limit cycle oscillations at any flight veloc- ity are derived. Finally, these analytic results are compared to the results of numerical simulations, and a good agree- ment is found. The effects of freeplay value and contact stiffness ratio on the limit cycle oscillation are also analyzed through numerical simulations of the original system. More- over, there exist multi-periods limit cycle oscillations and even complicated ＂chaotic＂ oscillations may occur, which are usually found in smooth nonlinear dynamic systems.

关键词： Freeplay nonlinearity ~ Typical airfoil section ~Limit cycle oscillations ~ Poincar6 map

Improvement in hydrogen storage performance of MgH_(2) by vanadium doped with ziF-8 derived a single-atom catalyst V-N-C

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Rare Metals 2024年第6期43卷 2623-2635页

作者： Fei-fan Hong wei-Tao Shi Ruo-Lin Zhao Yi fan zi-Qi Liu Si-Zhi Ding Hai-Zhen Liu Wen-Zheng Zhou Jin Guo Zhi-Qiang Lan Guangxi Novel Battery Materials Research Center of Engineering Technology and Center on Nanoenergy Research Guangxi Colleges and Universities Key Laboratory of Blue Energy and Systems IntegrationCarbon Peak and Neutrality Science and Technology Development InstituteSchool of Physical Science and TechnologyGuangxi UniversityNanning 530004China Nanning Engineering Technology Research Center for Power Transmission System of New Energy Vehicle Transportation CollegeNanning UniversityNanning 530200China

Herein,the successful preparation of a singleatom catalyst V-N-C using vanadium-doped zeolitic imidazolate framework(ziF)-8 as a precursor is *** experimental results showed that the V-N-C had a good promoting effect on the hydrogen storage performance of MgH_(2),and the optimal addition amount of V-N-C was 10wt%.The hydrogenation and dehydrogenation apparent activation energies of 10 wt%V-N-C-catalyzed MgH_(2)were reduced by 44.9 and 53.5 kJ·mol^(-1),respectively,compared to those of additive-free MgH_(2).The 10 wt%V-N-C-catalyzed MgH_(2)could reabsorb 5.92 wt%of hydrogen in 50 min at 150℃,with a capacity retention rate of 99.1%after 30 cycles of hydrogen absorption and *** analysis showed that V-N-C was partially transformed into VN and metallic V when it was milled with MgH_(2);the in-situ-formed VN and metallic V played an important role in improving the hydrogen storage performance of MgH_(2).This approach provides a potential solution for obtaining high-performance Mg-based hydrogen storage materials through synergistic interactions between V,N and C.

关键词： MgH_(2) Hydrogen storage materials Catalyst Hydrogen storage perormance

Evaluating spatial accessibility to healthcare services from the lens of emergency hospital visits based on floating car data

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International Journal of Digital Earth 2022年第1期15卷 108-133页

作者： wei Jiao wei Huang Hongchao fan School of Remote Sensing and Information Engineering Wuhan UniversityWuhanPeople’s Republic of China College of Surveying and Geo-Informatics Tongji UniversityShanghaiPeople’s Republic of China Department of Civil Engineering Ryerson UniversityTorontoCanada Department of Civil and Environmental Engineering Norwegian University of Science and TechnologyTrondheimNorway

Public medical facilities that are closely related to the health of residents have been recognised as one of the most crucial elements in sustainable urban *** the sake of social equality of medical services(especially for emergency medical conditions),the spatial distributions of medical resources need to be accurately measured and continuously *** study presents an effective method to examine night emergency hospital visit and analyse its spatiotemporal characteristics using float car data(FCD).By extracting the hospital service areas,the two-step floating catchment area(2SFCA)methodology was improved to calculate hospital ***,the balance between hospital accessibility and population density was *** addition,we investigated the relationship between individual hospital choice preferences and hospital level and analysed several factors that affect individual *** results help us understand the special requirements and need of emergency hospital travel in cities and identify areas where medical resources are *** can be used as guidance for urban hospital planning and *** the approach of hospital access behaviour investigation and the improved 2SFCA method can also provide insights for other activity-based travel behaviour research.

关键词： Floating car data hospital emergency travels hospital service areas hospital accessibility

Irreversible demagnetization mechanism of permanent magnets during electromagnetic buffering

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Defence Technology（防务技术） 2021年第3期17卷 763-774页

作者： zi-xuan Li Guo-lai Yang Yu-meng fan Jia-hao Li School of Mechanical Engineering Nanjing University of Science and TechnologyNanjingPR China

The permanent magnets will be irreversibly demagnetized under high temperature and high velocity during the electromagnetic *** this study,the magnetic field induced by eddy currents and the self-demagnetizing field of permanent magnet are taken into consideration together for demagnetization *** magnetic Reynolds number is used to express the eddy currents *** correction coefficient being expressed as the index of the air-gap width,the inner cylinder thickness,iron pole axial length and the permanent magnet demagnetization coefficient is introduced by magnetic path analysis to represent the self-demagnetization effect and the demagnetization *** electromagnetic buffer(EMB)prototype is tested under intensive impact loads of different strengths at room *** accuracy of the nonlinear irreversible demagnetization finite element model is verified by demagnetization on damping force,velocity and ***,high-velocity demagnetization and high-temperature demagnetization are analysed in order to obtain the distribution law of irreversible demagnetization.

关键词： EMB Irreversibly demagnetization Magnetic Reynolds number Correction coefficient

AN EQUIVALENT CONTINUUM METHOD OF LATTICE STRUCTURES

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Acta Mechanica Solida Sinica 2006年第2期19卷 103-113页

作者： fan Hualin Yang wei Department of Engineering Mechanics Tsinghua University Beijing 100084 China

An equivalent continuum method is developed to analyze the effective stiffness of three-dimensional stretching dominated lattice materials. The strength and three-dimensional plastic yield surfaces are calculated for the equivalent continuum. A yielding model is formulated and compared with the results of other models. The bedding-in effect is considered to include the compliance of the lattice joints. The predicted stiffness and strength are in good agreement with the experimental data, validating the present model in the prediction of the mechanical properties of stretching dominated lattice structures.

关键词： stretching dominated lattice materials equivalent continuum method effective stiffness yield surface bedding-in effect

Integration of association and computational methods reveals functional variants of LEPR gene for abdominal fat content in chickens

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Journal of Integrative Agriculture 2021年第10期20卷 2734-2748页

作者： LI Yu-dong WANG wei-jia LI zi-wei WANG Ning XIAO fan GAO Hai-he GUO Huai-shun LI Hui WANG Shou-zhi Key Laboratory of Chicken Genetics and Breeding Ministry of Agriculture and Rural AffairsHarbin 150030P.R.China Key Laboratory of Animal Genetics Breeding and ReproductionEducation Department of Heilongjiang ProvinceHarbin 150030P.R.China School of Animal Sciences and Technology Northeast Agricultural UniversityHarbin 150030P.R.China Fujian Sunnzer Biotechnology Development Co. Ltd.Guangze 354100P.R.China

Leptin receptor(LEPR)plays a vital role in obesity in humans and *** objective of this study is to assess LEPR functional variants for chicken adipose deposition by integration of association and in-silico analysis using a unique chicken population,the Northeast Agricultural University broiler lines divergently selected for abdominal fat content(NEAUHLF).Five online bioinformatics tools were used to predict the functionality of the single nucleotide polymorphisms(SNPs)in coding ***,the possible structure–function relationship of high confidence SNPs was determined by bioinformatics analyses,including the conservation and stability analysis based on amino acid residues,prediction of protein ligand-binding sites,and the superposition of protein tertiary ***,we analyzed the association between abdominal fat traits and 20 polymorphisms of chicken LEPR *** integrated results showed that rs731962924(N867I)and rs13684622(C1002R)could lead to striking changes in the structure and function of proteins,of which rs13684622(C1002R)was significantly associated with abdominal fat weight(AFW,P=0.0413)and abdominal fat percentage(AFP,P=0.0260)in ***,we are of the opinion that rs13684622(C1002R)may be an essential functional SNP affecting chicken abdominal fat deposition,and potentially applied to improvement of broiler abdominal fat in molecular marker-assisted selection(MAS)***,the coupling of association with computer electronic predictive analysis provides a new avenue to identify important molecular markers for breeders.

关键词： chicken LEPR nsSNPs bioinformatics tools abdominal fat content association analysis

The dynamic change of pore structure for low-rank coal under refined upgrading pretreatment temperatures

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Petroleum Science 2021年第2期18卷 430-443页

作者： Teng Li Cai-fang Wu zi-wei Wang College of Petroleum Engineering Xi’an Shiyou UniversityXi’an710065ShaanxiChina Shandong Key Laboratory of Depositional Mineralization and Sedimentary Mineral Shandong University of Science and TechnologyQingdao266590ShandongChina Shaanxi Key Laboratory of Advanced Stimulation Technology for Oil and Gas Reservoirs Xi’an Shiyou UniversityXi’an710065ShaanxiChina School of Resources and Geosciences China University of Mining and TechnologyXuzhou221008JiangsuChina

Pore structure characteristics are significant factor in the evaluation of the physical characteristics of low-rank *** this study,three low-rank coal samples were collected from the Xishanyao Formation,Santanghu Basin,and low-temperature liquid-nitrogen adsorption(LP-N2A)measurements were taken under various pretreatment *** to the continuous loss of water and volatile matter in low-rank coal,the total pore volume assumes a three-step profile with knee temperatures of 150°C and 240°***,the ash in the coal can protect the coal *** collapse mainly occurs for mesopores with aperture smaller than 20 *** with apertures smaller than 5 nm exhibit a continuous decrease in pore volume,whereas the pore volume of mesopores with apertures ranging from 5 to 10 nm increases at lower pretreatment temperatures(<150°C)followed by a faint *** for mesopores with apertures larger than 10 nm,the pore volume increases significantly when the pretreatment temperature reaches 300°*** pore structure of low-rank coal features a significant heating effect,the pretreatment temperature should not exceed 150°C when the LP-N2A is used to evaluate the pore structure of low-rank coal to effectively evaluate the reservoir characteristics of low-rank coal.

关键词： Low-rank coal Low-temperature liquid-nitrogen adsorption Pore structure Refined upgrading temperatures Heating effect

Pointwise Characterizations of Besov and Triebel–Lizorkin Spaces with Generalized Smoothness and Their Applications

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Acta Mathematica Sinica,English Series 2022年第4期38卷 623-661页

作者： zi wei LI Da Chun YANG Wen YUAN Laboratory of Mathematics and Complex Systems(Ministry of Education of China) School of Mathematical SciencesBeijing Normal UniversityBeijing 100875P.R.China

In this article,the authors first establish the point wise characterizations of Besov and Triebel-Lizorkin spaces with generalized smoothness on R;via the Hajlasz gradient sequences,which serve as a way to extend these spaces to more general metric measure ***,on metric spaces with doubling measures,the authors further prove that the Besov and the Triebel-Lizorkin spaces with generalized smoothness defined via Hajlasz gradient sequences coincide with those defined via hyperbolic *** an application,some trace theorems of these spaces on Ahlfors regular spaces are established.

关键词： Besov space Triebel-Lizorkin space generalized smoothness Hajlasz gradient hyperbolic filling trace