检索结果-南通市图书馆

Transactions of Nonferrous Metals Society of China 2014年第3期24卷 884-892页

作者： Neboja d.NIKOLI djendji dj.VATAG Vesna M.MAKSIMOVI Goran BRANKOVI ICTM- Institute of Electrochemistry University of Belgrade Faculty of Sciences University of Novi Sad Trg D. Obradovia 3 Novi Sad Serbia department of material science INN Vina University of Belgrade Institute for Multidisciplinary Research University of Belgrade Kneza Vieslava 1a Belgrade Serbia

lead powder obtained by potentiostatic electrodeposition from alkaline electrolyte, based on hydroxide ions, was investigated. The shape of lead crystals strongly depends on overpotentials of electrodeposition. The regular crystals are formed in the ohmic control. The shape of dendrites formed in the control of diffusion has a function of overpotentials of the electrodeposition. Increasing overpotential leads to branching of dendrites from primary type to those with developed tertiary branches. Formation of the very branchy dendrites of the strong （111） preferred orientation is explained on the basis of the affiliation of this electrolyte to the group of the complex Pb electrolytes.

关键词： lead powder electrodeposition crystal dendrite

基于气候分区与遥感技术的大兴安岭湿地信息提取

在线全文

学校读者我要写书评

暂无评论

生态学杂志 2017年第7期36卷 2068-2076页

作者：刘焕军盛磊于胜男赵慧颖高永刚秦乐乐王翔张新乐东北农业大学资源与环境学院哈尔滨150030 黑龙江省气象科学研究所哈尔滨150030

针对高山湿地遥感研究的复杂性,本文提出了一种基于气候分区、面向对象分层分割的高山湿地遥感提取方法。利用MOdIS归一化植被指数(NdVI)时间序列及数字高程模型(dEM)数据,在气候分区的基础上采用面向对象分类方法,进行大兴安岭地区的... 详细信息

针对高山湿地遥感研究的复杂性,本文提出了一种基于气候分区、面向对象分层分割的高山湿地遥感提取方法。利用MOdIS归一化植被指数(NdVI)时间序列及数字高程模型(dEM)数据,在气候分区的基础上采用面向对象分类方法,进行大兴安岭地区的湿地遥感提取,并分析了2001—2013年大兴安岭湿地的时空动态变化及成因。结果表明:基于MOdIS影像综合特征的面向对象方法,比基于像元的最大似然法和Logistic模型法提取湿地信息的精度更高,面向对象方法提取大兴安岭湿地制图精度为82%,Kappa系数为0.74;2001年大兴安岭地区湿地面积为414.89×104hm^2,2013年湿地面积为340.39×104hm^2,13年间湿地面积总体呈减少趋势;不同地区湿地增减趋势不同,湿地增加区域主要分布在塔河县和呼玛县,是由于2013年降雨量高于2001年降雨量引起的,而湿地农田化导致分布在甘南县和龙江县的湿地减少。研究成果将为高山湿地时空动态信息提取提供技术支持。

关键词：大兴安岭湿地 NdVI时间序列面向对象分类空间插值时空变化

Light hydrocarbon in ore-forming fluids and its constraints on ore genesis——A case study on Changkeng large-scale Au-Ag deposit, central Guangdong, China

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1999年第S2期44卷 58-61页

作者： d. l. Norman department of Earth & Environmental Sciences New Mexico Institute of Mining & Technology (NMT) Socorro NM87801 USA

ORGANIC matters in the ore-forming fluids are composed mainly of light hydrocarbons. Because of the small amount of hydrocarbons in fluid inclusions, it is quite difficult to study their behavior in mineralizing processes, excepting methane （CH4）. In this work, we used a high vacuum quadrupole gas massspectrometer system to determine the content and composition of light hydrocarbons (C1-7) in fluid inclusions in minerals collected from Changkeng Au-Ag deposit. The geological significance of the new data forgenesis of the deposit has been discussed briefly.

关键词： light hydrocarbons ore-forming fluid ore genesis Changkeng Au-Ag deposit.

Fifty years of finite elements——a solid mechanics perspective

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics letters 2012年第5期2卷 1-5页

作者： d.R.J.Owen Civil and Computational Engineering Centre Swansea University

The finite element method has been considered as one of the most significant engineering advances of the twentieth century. This computational methodology has made substantial impact on many fields in science and also has profoundly changed engineering design procedures and practice. This paper, mainly froln a solid mechanics perspective, and the Swansea viewpoint in particular, describes very briefly the origin of the methodology, then summaries selected milestones of the technical developments that have taken place over the last fifty years and illustrates their application to some practical engineering problems.

关键词： inite elements isoparametric representation elasto-plasticity finite strain mesh adaptiv ity discrete and multi-fracturing modelling

Wafer-scale quasi-layered tungstate-doped polypyrrole film with high volumetric capacitance

在线全文

学校读者我要写书评

暂无评论

Nano Research 2023年第4期16卷 4895-4900页

作者： Huabo Liu Jiaxing Liang John Watt Richard d.Tilley Rose Amal da-Wei Wang School of Chemical Engineering University of New South WalesSydneyNSW 2052Australia 2 Center for Integrated NanotechnologiesLos Alamos National LaboratoryLos AlamosNW 87545USA 3 School of ChemistryUniversity of New South WalesSydneyNSW 2052Australia

Layered materials are particularly attractive for supercapacitors because of their unique physical,electrical and chemical ***,we demonstrate a facile and scalable electrochemical deposition method for wafer-scale synthesis of quasilayered tungstate-doped polypyrrole films(named TALPy)with controllable thickness and *** as-prepared TALPy film exhibits a high gravimetric density and excellent volumetric capacitance,exceeding many high-performing carbon-and polymerbased film *** on combined results of ex-situ X-ray diffraction(XRd),Raman and X-ray photoelectron spectroscopy(XPS),it is determined that TALPy stores charge through an ion intercalation process accompanied by change in oxidation states of polypyrrole backbone,which is referred as intercalation *** these results suggest the great promise of electrochemical deposition as a scalable and controllable bottom-up approach for synthesizing quasi-layered conductive organic-inorganic hybrid films for electrochemical energy storage applications with high volumetric performance.

关键词： electrochemical deposition conductive polymer polypyrrole organic-inorganic hybrid supercapacitor intercalation pseudocapacitance

Large-diameter trees and deadwood correspond with belowground ectomycorrhizal fungal richness

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Ecological Processes 2023年第1期12卷 31-45页

作者： Joseph d.Birch James A.Lutz Soren Struckman Jessica R.Miesel Justine Karst department of Plant Soil and Microbial SciencesMichigan State University1066 Bogue StreetEast LansingMI 48824USA department of Wildland Resources and the Ecology Center Utah State University5230 Old Main HillLoganUT 84322-5230USA department of Renewable Resources University of Alberta751 General Services BuildingEdmontonAB T6G 2H1Canada

Background: Large-diameter trees have an outsized influence on aboveground forest dynamics, composition, and structure. Although their influence on aboveground processes is well studied, their role in shaping belowground fungal communities is largely unknown. We sought to test if (i) fungal community spatial structure matched aboveground forest structure;(ii) fungal functional guilds exhibited differential associations to aboveground trees, snags, and deadwood;and (iii) that large-diameter trees and snags have a larger influence on fungal community richness than smaller-diameter trees. We used MiSeq sequencing of fungal communities collected from soils in a spatially intensive survey in a portion of Cedar Breaks National Monument, Utah, USA. We used random forest models to explore the spatial structure of fungal communities as they relate to explicitly mapped trees and deadwood distributed across 1.15 ha of a 15.32-ha mapped subalpine forest. Results: We found 6,177 fungal amplicon sequence variants across 117 sequenced samples. Tree diameter, dead-wood presence, and tree species identity explained more than twice as much variation (38.7% vs. 10.4%) for ectomy-corrhizal composition and diversity than for the total or saprotrophic fungal communities. Species identity and dis-tance to the nearest large-diameter tree (≥ 40.2 cm) were better predictors of fungal richness than were the identity and distance to the nearest tree. Soil nutrients, topography, and tree species differentially influenced the composition and diversity of each fungal guild. Locally rare tree species had an outsized influence on fungal community richness. Conclusions: These results highlight that fungal guilds are differentially associated with the location, size, and species of aboveground trees. Large-diameter trees are implicated as drivers of belowground fungal diversity, particularly for ectomycorrhizal fungi.

关键词： Belowground ecology Ectomycorrhizal fungi Pinus flexilis Pinus longaeva Saprotrophic fungi Smithsonian ForestGEO Spatial dynamics Utah Forest dynamics Plot

同方期刊数据库

Enhanced thermoelectric performance of spark plasma sintered p-type Ca_(3-x)Y_(x)Co_(4)O_(9+δ)systems

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2020年第20期52卷 212-222页

作者： J.S.Cha d.H.Kim H.Y.Hong K.Park Faculty of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul05006Republic of Korea

Highly textured dense Ca3-xYxCo4 O9+δ(0≤x≤0.3)samples were fabricated by combining sol-gel process with spark plasma sintering(SPS).Y^3+substitution for Ca^2+simultaneously increased the Seebeck coefficient and reduced the thermal *** latter was attributed to the increase in lattice anharmonicity,structural distortion,and grain boundary area,which enhanced the phonon ***2.7Y0.3Co4 O9+δshowed the largest dimensionless figure-of-merit(ZT=0.194)at 1073 K because it had the largest Seebeck coefficient and the lowest thermal *** ZT value was 55%larger than that of undoped Ca3 Co4 O9(0.125 at 1073 K).Therefore,Y^3+substitution,sol-gel powder synthesis,and SPS are highly effective for enhancing the thermoelectric prope rties of Ca_(3)Co_(4)O_(9).

关键词： Electrical conductivity Ca_(3)Co_(4)O_(9) Thermoelectric properties Seebeck coefficient Thermal conductivity Spark plasma sintering

Temperature Effects on the Microstructures of Mg-Gd-Y Alloy Processed by Multi-direction Impact Forging

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English letters) 2020年第2期33卷 243-251页

作者： S.S.A.Shah d.Wu R.S.Chen G.S.Song School of Material Science and Engineering Anhui University of Technology The Group of Magnesium Alloys and Their Applications Institute of Metal ResearchChinese Academy of Sciences

A high strain rate multi-directional impact forging(MdIF) was applied to a solutionized Mg-Gd-Y-Zr alloy in the temperature range of 350-500℃.Results demonstrate that the dominant deformation mode is twinning at a temperature below 400℃,whereas at a medium temperature of 450℃ considerable continuous dynamic recrystallization was promoted by{10-12} extension *** a higher temperature of 500℃,twinning activation was *** dRX grains were observed but their sizes were much bigger than those resulting from the MdIFed 50 passes at 450℃,which are ascribed to the larger grain boundary mobility and atomic diffusion at 500℃.Moreover,a non-basal weak texture was gained afterward MdIF at each temperature,which is credited to the MdIF process and the minor strain applied in each pass.

关键词： Magnesium alloys Twinning dynamic recrystallization Forging Texture

New superhydrophobic composite coatings on Mg-Mn-Ce magnesium alloy

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第5期11卷 1721-1739页

作者： K.V.Nadaraia S.N.Suchkov I.M.Imshinetskiy d.V.Mashtalyar d.Yu.Kosianov E.A.Belov S.L.Sinebryukhov S.V.Gnedenkov Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok690022Russia Far Eastern Federal University Vladivostok690922Russia

A novel combined method for the formation of composite coatings on the Mg-Mn-Ce alloy is *** like matrix was formed on the Mg alloy surface by the plasma electrolytic *** the samples were subsequently processed by dip-coating in an alcohol suspension of superdispersed polytetrafluoroethylene and spraying with the tetrafluoroethylene telomers ***,OSP,and SPM was used to study structure of formed *** was established by measurements of CA and CAH,as well as surface free energy calculations that formed coatings demonstrate superhydrophobic properties due to the presence of an irregular hierarchical surface structure and low surface free energy of *** coating preserves its hydrophobic properties after exposure to high and low temperatures,for a long time as well as being in corrosive *** and XRd data analysis confirmed the presence of organofluorine compounds in the composite layers,including in the form of crystalline *** potentiodynamic polarization test and EIS,it was found that the resulting coatings significantly increase the corrosion resistance of Mg *** data are also confirmed by salt spray tests for 40 *** of fluoropolymers additionally decrease coatings coefficient of friction.

关键词： Magnesium alloy Plasma electrolytic oxidation Superhydrophobicity Fluoropolymers Composite coatings

Application of Genetic Algorithms in Identification ofLinear Time-Varying System

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2000年第1期14卷 58-62页

作者： Zhichun Mu KeLiu Zichao Wang datai Yu d. Koshal d. Pearce Information Engineering School, University of Science & Technology Beijing, Beijing 100083, China School of Engineering, University of Brighton, Brighton, UK Information Engineering School University of Science and Technology Beijing Beijing 100083 China School of Engineering University of Brighton Brighton United Kingdom

By applying genetic algorithms (GA) to on-line identification of linear time-varying systems; a number of modifications are made to the Simple Genetic Algorithm to improve the performance of the algorithm in identification applications. The simulation results indicate that the method is not only capable of following the changing parameters of the system, but also has improved the identification accuracy compared with that using the least square method.

关键词： genetic algorithm, system identification linear system