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Supersonic Turbulent Boundary Layer： DNS and RANS

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Chinese Physics Letters 2007年第3期24卷 763-766页

作者：徐晶磊马晖扬 Department of Physics Graduate School of the Chinese Academy of Sciences PO Box 3908 Beijing 100049

We assess the performance of a few turbulence models for Reynolds averaged Navier-Stokes （RANS） simulation of supersonic boundary layers, compared to the direct numerical simulations （DNS） of supersonic flat-plate turbulent boundary layers, carried out by Gao et al. [Chin. Phys. Lett. 22（2005）1709] and Huang et al. [Sci. Chin. 48 （2005） 614], as well as some available experimental data. The assessment is made for two test cases, with incoming Mach numbers and Reynolds numbers M = 2.25, Re = 365, 000//in, and M = 4.5, Re = 1.7 × 10^7/m, respectively. It is found that in the first case the prediction of RANS models agrees well with the DNS and the experimental data, while for the second case the agreement of the DNS models with experiment is less satisfactory. The compressibility effect on the RANS models is discussed.

关键词： DIRECT NUMERICAL-SIMULATION MODEL

Longitudinal Single Bunch Instability Caused by Wake Field of Electron Cloud

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Chinese Physics Letters 2009年第2期26卷 92-94页

作者：刘瑜冬于程辉 Institute of High Energy Physics Chinese Academy of Sciences PO Box 918 Beijing 100049

The electron cloud accumulated in the vicinity of positron beam generates longitudinal electric field during the passage of bunch. The longitudinal interaction between bunch and electron cloud can lead to the distortion of the bunch shape. We use a simple analytic formula to calculate the longitudinal electric field due to electron cloud. Based on the longitudinal wake field, the macro-particle tracking method is used to simulate the variation of bunch longitudinal profile in different electron cloud densities and the simulation also shows that the synchrotron oscillation tune is slightly shifted by the wake field. By comparing the simulation results and the analytical estimation from potential distortion theory, the longitudinal wake field from electron cloud can be seen as a potential well effect.

关键词： field emission molybdenum dioxide enhancement factor

A Modified Protocol of Quantum Key Distribution Based on Entanglement Swapping

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Chinese Physics Letters 2007年第9期24卷 2479-2481页

作者：黄鑫李书民王安民 Department of Modern Physics University of Science and Technology of China PO Box 4 Hefei 230026

By comparing Cabello＇s addendum to his quantum key distribution protocol [Phys. Rev. A 64 （2001） 024301], we propose a more convenient modified protocol based on the entanglement swapping which is secure against the eavesdropping strategy addressed by Zhang et al. [Phys. Rev. A 63 （2001）036301] and other existing types of attack.

关键词： CHANNELS STATES

Design of a new static solar concentrator with a high concentration ratio and a large acceptance angle based on bifacial solar cells

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Clean Energy 2023年第3期7卷 509-518页

作者： Adnan Shariah Emad Hasan Physics Department Jordan University of Science and TechnologyPO Box 3030IrbidJordan

Solar concentrators are used in solar photovoltaic systems to lower the cost of producing *** this situation,fewer solar cells can be used,lowering the overall cost of the *** purpose of this article is to design,construct,install and test a stationary(non-tracking)concentrating system in Irbid,*** solar cells are used in the *** concentrator designs(with the same concentration ratio)are experimentally ***-A has a parabolic shape in the lower part but flat reflecting walls,whereas Conc-B has a standard compound parabolic shape in all *** receiving solar cells are arranged in three distinct positions in each *** results reveal that the output power from both concentrators is affected by the placement of the receiving solar cells within the *** has also been found that concentrators with flat reflecting walls perform better than those with parabolic reflecting ***-A’s power collection is~198%greater than that of a non-concentrating *** Conc-B is used,the increase in power is~181%.

关键词： bifacial solar cell non-tracking system parabolic trough concentration PV concentrators

Remote sensing of quality traits in cereal and arable production systems:A review

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The Crop Journal 2024年第1期12卷 45-57页

作者： Zhenhai Li Chengzhi Fan Yu Zhao Xiuliang Jin Raffaele Casa Wenjiang Huang Xiaoyu Song Gerald Blasch Guijun Yang James Taylor Zhenhong Li College of Geodesy and Geomatics Shandong University of Science and TechnologyQingdao 266590ShandongChina Key Laboratory of Quantitative Remote Sensing in Ministry of Agriculture and Rural Affairs Information Technology Research CenterBeijing Academy of Agriculture and Forestry SciencesBeijing 100097China Institute of Crop Sciences Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Physiology and EcologyMinistry of Agriculture and Rural AffairsBeijing 100081China DAFNE Universitàdella TusciaVia San Camillo de Lellis01100 ViterboItaly Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijing 100094China International Maize and Wheat Improvement Center(CIMMYT) PO Box 5689Addis AbabaEthiopia ITAP Univ.MontpellierINRAEInstitut AgroMontpellier 34000France College of Geological Engineering and Geomatics Chang’an UniversityXi’an 710054ShaanxiChina

Cereal is an essential source of calories and protein for the global *** predicting cereal quality before harvest is highly desirable in order to optimise management for farmers,grading harvest and categorised storage for enterprises,future trading prices,and policy *** use of remote sensing data with extensive spatial coverage demonstrates some potential in predicting crop quality *** studies have also proposed models and methods for predicting such traits based on multiplatform remote sensing *** this paper,the key quality traits that are of interest to producers and consumers are *** literature related to grain quality prediction was analyzed in detail,and a review was conducted on remote sensing platforms,commonly used methods,potential gaps,and future trends in crop quality *** review recommends new research directions that go beyond the traditional methods and discusses grain quality retrieval and the associated challenges from the perspective of remote sensing data.

关键词： Remote sensing Quality traits Grain protein Cereal

Exclosures restored the density and root colonization of arbuscular mycorrhizal fungi in Tigray, Northern Ethiopia

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Ecological Processes 2017年第1期6卷 339-350页

作者： Emiru Birhane Kide Mogos Gebremedihin Tewodros Tadesse Mengsteab Hailemariam Negasi Solomon Department of Land Resources Management and Environmental protection Mekelle UniversityPO Box 231MekelleEthiopia Faculty of Environmental Sciences and Natural Resource Management Norwegian University of Life SciencesPO Box 50031432ÅsNorway Department of Natural Resource Economics and Management Mekelle UniversityPO Box 231MekelleEthiopia

Introduction:Exclusion of grazing animals and tree plantations were among the methods used for the restoration of degraded lands in tropical semiarid *** can foster secondary forest succession by improving soil conditions and modifying microclimate for understory *** paper compared the arbuscular mycorrhizal fungi(AMF)spore density,root colonization of woody plants and soil chemical properties under exclosure with increasing age,and grazing land at different slope ***:The study was conducted in northern Ethiopia from 12 exclosure sites paired each with adjacent grazing land in total from 24 sites with four treatments replicated three *** the entire study,216 plots were examined of which 108 were in exclosures and 108 in communal grazing *** were four age classes and three slope positions in each of the land *** soil and root samples were collected using nested plots measuring 100m2 from four sides of 1763 plants for spore enumeration and root *** for chemical properties were collected from the four corners and center of 5 m×5 m ***:All the 61 woody plant species that belong to 41 families were colonized by *** density and root colonization were significantly higher in exclosures as compared to grazing land and increased with increasing ages of *** slope had significantly higher spore density and root colonization than middle and upper *** chemical properties were significantly higher in the exclosure,oldest age of exclosure,and foot slope position(except P).AMF spore density and root colonization were significantly positively correlated with soil chemical ***:Exclosures are helpful to restore the AMF spore density and root colonization of woody species and soil fertility.

关键词： Spore density Root colonization Age of exclosure Slope position

Sintering behavior of combusted iron powder in a packed bed reactor with nitrogen and hydrogen

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Particuology 2023年第12期83卷 8-17页

作者： C.J.M.Hessels A.H.J.Smeets G.Finotello N.G.Deen Y.Tang power and Flow Group Department of Mechanical EngineeringEindhoven University of TechnologyPO Box 5135600MBEindhoventhe Netherlands Eindhoven Institute for Renewable Energy Systems(EIRES) PO Box 5135600MBEindhoventhe Netherlands

Sintering behavior of micron-sized combusted iron powder is studied in a packed bed reactor,at various temperatures under inert(nitrogen)and reducing(hydrogen)*** tests are subsequently used to quantify the degree of sintering.A sintering model,based on the formation of a solid bridge through solid state surface diffusion of iron atoms,matches the experimental *** of combusted iron occurs at temperatures≥575°C in both nitrogen and hydrogen atmospheres and increases exponentially with *** observed decrease in reduction rate at high temperatures is not caused by the sintering process but by the formation of wüstite as an intermediate species,leading to the formation of a dense iron *** whiskers form at high temperatures(≥700°C)in combination with low reduction rates(≤25 vol%H2),leading to the production of sub-micron fines.

关键词： Metal energy carrier Combusted iron Whiskers Solid bridge force Sintering

Comparison of the effect of carbon,halloysite and titania nanotubes on the mechanical and thermal properties of LDPE based nanocomposite films

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Chinese Journal of Chemical Engineering 2018年第2期26卷 428-435页

作者： Khaliq Majeed Mariam Al Ali AlMaadeed Moustafa M.Zagho Center for Advanced Materials Qatar UniversityPO Box 2713DohaQatar Department of Chemical Engineering COMSATS Institute olin formation TechnologyLahorePakistan Materials Science and Technology Program Qatar UniversityPO Box 2713DohaQatar

In this study, titania nanotubes （TNTs） were prepared by hydrothermal method with the aim to compare the properties of these one-dimensional tubular nanostructures＇ reinforced nanocomposites with the carbon and halloysite nanotubes＇（CNTs and HNTs, respectively） reinforced nanocomposites. Low density polyethylene （LDPE） was used as the matrix material. The prepared nanocomposites were characterized and compared by means of their morphological, mechanical and thermal properties. SEM results showed enhanced interracial interaction and better dispersion of TNTs and HNTs into LDPE with the incorporation of a MAPE compatibilizer, however, these interactions seem to be absent between CNTs and LDPE, and the CNTs remained agglomerated. Contact angle measurements revealed that CNT filled nanocomposites are more hydrophilic than HNT composites, and less than TNT composites. CNTs provided better tensile strength and Young＇s modulus than HNT and TNT nanocomposites, a 42% increase in tensile strength and Young＇s modulus is achieved compared to LDPE. Tear strength improvement was noticed in the TNT composites with a value of 35.4 N. mm -1, compared to CNT composites with a value of 25.5 *** 1 -s- 1. All the prepared nanocomposites are more thermally stable than neat LDPE and the best improvement in thermal stability was observed for CNT reinforced nanocomposites. CNTs depicted the best improvement in tensile and thermal properties and the MAPE compatibilizer effective- ness regarding morphological, mechanical and thermal properties was only observed for TNT and HNT systems.

关键词： Hydrothermal Nanostructure Nanotube Nanocomposite Mechanical properties Thermal properties

Effects of Shock Pressure on Transition Pressure in Zr

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Chinese Physics Letters 2007年第3期24卷 784-785页

作者：李英华张林蔡灵仓 Laboratory of Shock Wave and Detonation Physics Research PO Box 919-102 Mianyang 621900

Measurements of free surface velocity profiles of high-purity Zr samples under shock-wave loading are performed to study the dynamic strength and phase transition parameters. The peak pressure of the compression waves is within the range from 9 to 14 GPa, and the Hugoniot elastic limit is 0.5 GPa. An anomalous structure of shock waves is observed due to the α - ω phase transition in Zr. Shock pressure has effects on transition pressure which increases with increasing compression strength, and the stronger shocks have a lower transit time.

关键词： RELEASE BEHAVIOR ZIRCONIUM