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Preparation and performances of bulk porous Al foams impregnated with phase-change-materials for thermal storage

Progress in Natural Science:Materials International 2012年第5期22卷 440-444页

作者： Jinghua Jiang a,b,Yingying Zhu b,Aibin Ma a,b,Donghui yang b,c,Fumin Lu b,Jianqing Chen b,Jun Shi b,Dan Song a,b a National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,Hohai University,Nanjing 210098,China b College of Mechanics and Materials,Hohai University,Nanjing 210098,China c Department of Mechanical and Aerospace Engineering,North Carolina State University,Raleigh,NC 27695-7919,USA National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing 210098 China College of Mechanics and Materials Hohai University Nanjing 210098 China Department of Mechanical and Aerospace Engineering North Carolina State University Raleigh NC 27695-7919 USA

Shape-stabilized phase change materials(PCMs) exhibit desirable thermal storage properties and are used for energy conservation *** study is focused on the preparation and thermal-/dynamic-mechanical properties of the bulk porous Al foams impregnated with organic PCMs such as paraffins and stearic *** results indicated that the new shape-stabilized PCMs composites could be produced by a simple and eco-friendly constant-pressure impregnation *** filling fraction of PCMs was approximately more than 80% for the impregnated samples with vacuuming or without *** shape-stabilized PCMs/Al-foam composites exhibited considerable latent thermal storage potential for good interface,desirable phase-change temperature range and latent heat values(72.9kJ/kg for the paraffin/Al-foam composite and 66.7kJ/kg for the stearic acid/Al-foam composite).Moreover,the impregnation of PCMs improved the dynamic-compression yield strength,durability and resistance to oxidation of Al foams and made its ideal energy-saving materials.

关键词： Phase change materials Porous Al foams Composites Thermal storage Dynamic mechanical properties

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Covarying modes of the Pacific SST and northern hemispheric midlatitude atmospheric circulation anomalies during winter

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Progress in Natural Science:Materials International 2008年第10期18卷 1261-1270页

作者： Yimin Zhu~(a,b,*) Xiuqun yang~a Qian Xie~b Yongqiang Yu~c ~a Department of A tmospheric Science,Nanjing University,Nanjing 210093,China ~b Institute of Meteorology,PLA University of Science and Technology,Nanjing 211101,China ~c LASG,Institute of Atmospheric Physics,Chinese Academy of Sciences,beijing 100029,China Department of Atmospheric Science Nanjing University Nanjing 210093 China Institute of Meteorology PLA University of Science and Technology Nanjing 211101 China LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

The interannual-to-interdecadal relationship between the Pacific sea surface temperature (SST) and the northern hemispheric midlati- tude’s atmosphere represented by the circumpolar vortex was documented with the global oceanic and atmospheric reanalysis data of recent 50 *** covarying modes of the Pacific SST and northern circumpolar vortex anomalies during winter were examined using the sin- gular value decomposition and wavelet analysis *** is the interannual,ENSO-related mode and the other is the interdecadal, North Pacific SST-related mode with a period of around 20 *** two modes exhibit distinct spatial *** the interannual mode,the SST anomaly is characterized by a typical ENSO pattern with the principal signature in the tropical eastern Pacific and secondary one in the central North Pacific,while the atmospheric anomaly is regional,characterized by a Pacific-North American *** the inter- decadal mode,large SST anomaly is located in the central North Pacific,while the atmospheric anomaly is zonally global,associated with the midlatitute’s standing long-wave *** the central North Pacific is colder,the long-wave is stronger,and vice *** investigations suggest that the interdecadal mode could involve an interaction between "two oceans and an atmosphere".

关键词： Sea surface temperature Atmospheric circulation ENSO Decadal variability

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THERMAL STRUCTURAL DISORDER AND MELTING TRANSITION IN HIGH-ANGLE GRAIN-bOUNDARY: A MOLECULAR-DYNAMICS STUDY

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Acta Metallurgica Sinica(English Letters) 1998年第5期11卷 365-375页

作者： S.J.Zhao Y.C.Wang J.Q.You Q.b.yang L.G.Zhou H.Q.Ye Xiangtan Univ Xiangtan China

A structural transition in the fcc ∑=5 (120)/[001] high-angle tilt grain-boundary(Gb)is investigated by molecular-dynamics simulation. The calculations have been performed at various temperutures and the thermodynamic melting point Tm of the model system is determined by using a many-body potential fitted to copper. A thermal disorder transition in the Gb region occurs well below the melting point. Our results indicate that such a transition is a continuous process and there is no evidence of premelting, which is entirely in accord with experiment results and theoretical *** we also observed that melting initiated at the interface and then propagated into the bulk quickly at or above Tm.

关键词： moleculandynamics grainboundary structural transition

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Finite frequency H∞ filtering for uncertain discrete-time switched linear systems

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Progress in Natural Science:Materials International 2009年第11期19卷 1625-1633页

作者： Dawei Ding~(a,*),Guanghong yang~(a,b) a College of Information Science and Engineering,Northeastern University,Shenyang 110004,China b Key Laboratory of Integrated Automation of Process Industry,Ministry of Education,Northeastern University,Shenyang 110004,China College of Information Science and Engineering Northeastern University Shenyang 110004 China Key Laboratory of Integrated Automation of Process Industry Ministry of Education Northeastern University Shenyang 110004 China

This paper is concerned with the problem of robust H∞filtering for discrete-time switched linear systems with polytopic uncertainties in the finite frequency *** on the generalized Kalman-Yakubovich-Popov(GKYP) lemma and switched parameter-dependent Lyapunov functions,a switched full-order filter is designed such that the corresponding filtering error system is asymptotically stable and satisfies a prescribed finite frequency H∞performance *** with the existing full frequency approaches,the proposed finite frequency one receives better results for the cases in which the frequency ranges of noises are known.A numerical example is given to illustrate the effectiveness of the proposed method.

关键词： Switched systems Filtering Finite frequency GKYP lemma Linear matrix inequalities(LMIs)

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A transmission electron microscopy study of microscopic causes for localized-corrosion morphology variations in the AA7055 Al alloy

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Journal of Materials Science & Technology 2018年第10期34卷 1719-1729页

作者： X.b. yang J.H. Chen G.H. Zhang L.P. Huang T.W. Fan Y. Ding X.W. Yu Center for High-Resolution Electron Microscopy College of Materials Sdence and Engineering Hunan University Changsha Hunan 410082 China Department of Applied Physics School of Physics and Electronics Hunan University Changsha Hunan 410082 China

by Using （scanning） transmission electron microscopy, localized-corrosion morphology variations of the AA7055 AIZn（Cu）Mg alloy with different thermal processes and their underlying microscopic causes were investigated systematically. Our study shows that the corrosion resistance of the nanoscale precipitates varies with their structure type and Cu-content. Just like the Al-matrix, the early-stage precipitates are corrosion resistant, as compared with the ηp/η-precipitates without high Cu-content. With a high Cu-content, however, the η-precipitates become most corrosion resistant among all phases involved. Hence, tailoring the precipitate microstructure and chemistry though thermal processes may change the overall corrosion morphology and improve corrosion resistance property of the alloy.

关键词： Aluminum alloys Precipitates Corrosion Electron microscopy

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Phylogenetic relationship and morphological evolution in the subfamily Limenitidinae(Lepidoptera:Nymphalidae)

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Progress in Natural Science:Materials International 2008年第11期18卷 1357-1364页

作者： Min Zhang~a yang Zhong~b Tianwen Cao~c Yupeng Geng~b Yuan Zhang~b Ke Jin~b Zhumei Ren~a Rui Zhang~a Yaping Guo~a Enbo Ma~(a,*) a Research Institute of Applied biology and College of Life Science and Technology,Shanxi University,Taiyuan,Shanxi 030006,China b School of Life Sciences,Fudan University Shanghai 200433,China c Institute of Plant Protection,Shanxi Academy of Agricultural Science,Taiyuan 030031,China Research Institute of Applied biology and College of Life Science and Technology Shanxi University Taiyuan Shanxi 030006 China School of Life Sciences Fudan University Shanghai 200433 China Institute of Plant Protection Shanxi Academy of Agricultural Science Taiyuan 030031 China

The mitochondrial cytochrome oxidase subunit I(COI)gene and the nuclear elongation factor 1α(EF-1α)gene were sequenced from 29 species of Nymphalidae(Nymphalidae,Lepidoptera).Phylogenetic trees were constructed based on the sequences determined from the 29 species and sequences of other 36 species deposited in Genbank using the neighbor-joining(N J),maximum likelihood(ML)and bayesian methods with Libythea celtis(Libytheinae)as the *** phylogenetic trees indicated four major *** A includes three subfamilies:Apaturinae,Nymphalinae,and Limenitidinae,excluding the tribe Limenitidini;Clade b includes the subfam- ilies Heliconiinae and the tribe Limenitidini;Clade C includes Satyrinae,Calinaginae,Charaxinae and Morphinae;and Clade D includes subfamily *** study suggested that the tribes Pseudergolini,biblidini,Limenitidini and Cyrestidini should be considered as subfamilies and confirmed the interspecific relationships within the subfamily Pseudergolinae,namely Amnosia +(Pseudergolis +(Stibo- chiona + Dichorragia)).We then mapped three morphological characters(spot of anal angle,eyespots,and process from outer margin of hind wing)onto the phylogenetic tree constructed by ML analysis using the combined sequence *** on this the evolutionary patterns of these morphological characters were identifed,they indicated that the three characters evolved repeatedly in the family Nymphalidae.

关键词： Nymphalidae Limenitidinae Mitochondrial DNA cytochrome oxidase subunitⅠgene(COI) Nuclear elongation factor 1αgene(EF-1α) Molecular phylogeny Character evolution

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An Experimental Study on High Temperature and Low Oxygen Air Combustion

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Journal of Thermal Science 2000年第2期9卷 169-175页

作者： W.b. Kim D.H. Chung J.b. yang D.S. Noh Korea Institute of Energy Research, 71-2 Jangdong, Yusung Ku, Taejon, Korea Korea Institute of Energy Research Taejon Korea

High temperature preheated and diluted air combustion has been confirmed as the technology, mainly applied to industrial furnaces and kilns, to realize higher thermal efficiency and lower emissions. The purpose of this study was to investigate fundamental aspects of the above-mentioned combustion experimentally and to compare with those in ordinary hydrocarbon combustion with room temperature air. The test items were exhaust gas components of CO, NOx, flame shape and radical components of CH, OH and C2,which were measured with gas analyser, camera and ICCD(Intensified Charged - Coupled Device) camera. Many Phenomena as results appeared in combustion with the oxidizer, low oxygen concentration and extremely high temperature air, such as expansion of the flammable limits, increased flame propagation speed, it looked so strange as compared with those in existing combustion technology. We confirmed that such extraordinary phenomena were believable through the hot-test experiment.

关键词： high temperature air combustion diluted air blue-green flame radicals NOx ICCD camera hot-test

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Ramet population ecology of Panicum virgatum in the field–Competitively random growth of ramets and foraging behavior of ramet populations

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Progress in Natural Science:Materials International 2008年第7期18卷 901-906页

作者： Xinguo yang a,*, Tianlong Wu b, Xu Chengb a College of Resources and Environmental Sciences, China Agricultural University, beijing 100193, P.R. China b College of Agriculture and biotechnology, China Agricultural University, beijing 100193, P.R. China College of Resources and Environmental Sciences China Agricultural University Beijing 100193 P.R. China College of Agriculture and biotechnology China Agricultural University Beijing 100193 P.R. China

The authors investigated the heterogeneous size patterns and dynamic growth of the ramet population of Panicum virgatum, a clonal caespitose plant, limited to the space occupied by a ramet bunch and the time of the ramet yearly life cycle, to understand the ecology of clonal caespitose plants in the field, where the ramet bunch generally consisted of more than one genet. Dynamic life tables for ramet populations were established by the replacement of living ramets at the present time with "dead" ones in past time. These tables revealed stable coexisting patterns of isometric and allometric growing processes of ramets in mass and height respectively, which approximately followed the historic trajectory of a density-independent population. The ecology of clonal caespitose plants is further discussed based on the competitively random growth of ramet individuals, including the scale of foraging behavior. In the field, the ramet population ecol- ogy of switchgrass may be a statistical result of competitively random growth of ramet individuals. The foraging behavior of a ramet population could then be presented as a process in which ramet individuals competed with each other for light and grew randomly, while at the same time a relatively stable dynamic growth pattern was apparent at the level of the ramet population, and the functional leaves were placed properly in time and space.

关键词： Caespitose clone Ramet population Panicum virgatum Life table Phenotypic plasticity Foraging behavior

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Influence of oxygen gas content on the structural and optical properties of ZnO thin films deposited by RF magnetron sputtering at room temperature

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Rare Metals 2011年第2期30卷 170-174页

作者： LIU baoting ZHOU yang ZHENG Hongfang LI Mana GUO Zhe HAO Qingxun PENG Yingcai College of Physics Science and Technology Hebei University Baoding 071002 China baoding University Baoding 071000 China College of Electronic and Information Engineering Hebei University Baoding 071002 China

Zinc oxide （ZnO） thin films were deposited on sapphire （0001） substrates at room temperature by radiofrequency （RF） magnetron sputtering at oxygen gas contents of 0%, 25%, 50% and 75%, respectively. The influence of oxygen gas content on the structural and optical properties of ZnO thin films was studied by a surface profile measuring system, X-ray diffraction analysis, atomic force microscopy, and UV spectro- photometry. It is found that the size of ZnO crystalline grains increases first and then decreases with the increase of oxygen gas content, and the maximum grain size locates at the 25% oxygen gas content. The crystalline quality and average optical transmittance （〉90%） in the visi- ble-light region of the ZnO film prepared at an oxygen gas content of 25% are better than those of ZnO films at the other contents. The obtained results can be attributed to the resputtefing by energetic oxygen anions in the growing process.

关键词： thin films zinc oxide magnetron sputtering oxygen structural properties optical properties

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Design and optimization of the composition and mechanical properties for non-equiatomic CoCrNi medium-entropy alloys

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Journal of Materials Science & Technology 2023年第8期139卷 232-244页

作者： J.X.Yan Z.J.Zhang P.Zhang J.H.Liu H.Yu Q.M.Hu J.b.yang Z.F.Zhang Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Chongqing Jiaotong UniversityChongqing 400074China chool of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China School of Information Science and Engineering Shenyang University of TechnologyShenyang 111003China

The development of multi-principal element alloys(MPEAs,also called as high-or medium-entropy al-loys,HEAs/MEAs)provides tremendous possibilities for materials ***,designing MPEAs with desirable mechanical properties confronts great challenges due to their vast composition *** this work,we provide an essential criterion to efficiently screen the CoCrNi MEAs with outstanding strength-ductility *** negative Gibbs free energy difference△E_(FCC-bCC)between the face-centered cubic(FCC)and body-centered cubic(bCC)phases,the enhancement of shear modulus G and the decline of stacking fault energy(SFE)γ_(isf)are combined as three requisites to improve the FCC phase stability,yield strength,deformation mechanisms,work-hardening ability and ductility in the *** effects of chemical composition on△E_(FCC-bCC),G andγisf were investigated with the first principles calculations for Co_(x)Cr_(33)Ni_(67-x),Co_(33)Cr_(y)Ni_(67-y)and Co_(z)Cr_(66-z)Ni_(34)(0≤x,y≤67 and 0≤z≤66)*** on the essential criterion and the calculation results,the composition space that displays the neg-ative Gibbs free energy difference△E_(FCC-bCC),highest shear modulus G and lowest SFEγ_(isf)was screened with the target on the combination of high strength and excellent *** this context,the optimal composition space of Co-Cr-Ni alloys was predicted as 60 at.%-67 at.%Co,30 at.%-35 at.%Cr and 0 at.%-6 at.%Ni,which coincides well with the previous experimental evidence for Co_(55)Cr_(40)Ni_(5)*** valid-ity of essential criterion is further proved after systematic comparison with numerous experimental data,which demonstrates that the essential criterion can provide significant guidance for the quick exploitation of strong and ductile MEAs and promote the development and application of MPEAs.

关键词： Medium-entropy alloys First-principles calculations Phase stability Stacking-fault energy Strength Ductility

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