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Adaptive Boundary and Semantic Composite Segmentation Method for Individual Objects in Aerial Images
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作者 Ying Li Guanghong Gong +1 位作者 Dan Wang Ni Li 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第9期2237-2265,共29页
There are two types of methods for image segmentation.One is traditional image processing methods,which are sensitive to details and boundaries,yet fail to recognize semantic information.The other is deep learning met... There are two types of methods for image segmentation.One is traditional image processing methods,which are sensitive to details and boundaries,yet fail to recognize semantic information.The other is deep learning methods,which can locate and identify different objects,but boundary identifications are not accurate enough.Both of them cannot generate entire segmentation information.In order to obtain accurate edge detection and semantic information,an Adaptive Boundary and Semantic Composite Segmentation method(ABSCS)is proposed.This method can precisely semantic segment individual objects in large-size aerial images with limited GPU performances.It includes adaptively dividing and modifying the aerial images with the proposed principles and methods,using the deep learning method to semantic segment and preprocess the small divided pieces,using three traditional methods to segment and preprocess original-size aerial images,adaptively selecting traditional results tomodify the boundaries of individual objects in deep learning results,and combining the results of different objects.Individual object semantic segmentation experiments are conducted by using the AeroScapes dataset,and their results are analyzed qualitatively and quantitatively.The experimental results demonstrate that the proposed method can achieve more promising object boundaries than the original deep learning method.This work also demonstrates the advantages of the proposed method in applications of point cloud semantic segmentation and image inpainting. 展开更多
关键词 Semantic segmentation aerial images composite method traditional image processing deep learning
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Synthesis and Characterization of Hollow Strontium Carbonate Pompons by Composite Soft Template Method
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作者 LI Bibo DONG Xiufang +4 位作者 LI Yu SONG Jian XIE Wuxi ZHANG Wei LIU Yunfei 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第6期1434-1439,共6页
The hollow strontium carbonate pompons was synthesized for the first time by a controlled reaction precipitation method with sodium dodecyl benzene sulfonate(SDBS)and polyvinyl pyrrolidone(PVP)work together as templat... The hollow strontium carbonate pompons was synthesized for the first time by a controlled reaction precipitation method with sodium dodecyl benzene sulfonate(SDBS)and polyvinyl pyrrolidone(PVP)work together as template.The sampled particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM),nitrogen adsorption-desorption measurement,X-ray diffraction(XRD),Energy dispersive X-Ray spectroscopy(EDX),Fourier transform infrared spectroscopy(FTIR),Thermogravimetric analysis and differential scanning calorimetry(TGA-DSC),etc.It is shown that the assynthesized hollow strontium carbonate pompons with the size of about 2μm consist of flake-like particles under the optimal reaction conditions.The formation mechanism of hollow strontium carbonate pompons was preliminarily explored. 展开更多
关键词 strontium carbonate hollow structure pompons composite soft template method
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Differently implicational α-universal triple I restriction method of (1, 2, 2) type 被引量:5
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作者 Yiming Tang Fuji Ren Yanxiang Chen 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2012年第4期560-573,共14页
From the viewpoints of both fuzzy system and fuzzy reasoning, a new fuzzy reasoning method which contains the α- triple I restriction method as its particular case is proposed. The previous α-triple I restriction pr... From the viewpoints of both fuzzy system and fuzzy reasoning, a new fuzzy reasoning method which contains the α- triple I restriction method as its particular case is proposed. The previous α-triple I restriction principles are improved, and then the optimal restriction solutions of this new method are achieved, especially for seven familiar implications. As its special case, the corresponding results of α-triple I restriction method are obtained and improved. Lastly, it is found by examples that this new method is more reasonable than the α-triple I restriction method. 展开更多
关键词 fuzzy reasoning fuzzy system triple I method triple Irestriction method compositional rule of inference method.
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NEW FEATURE SELECTION METHOD IN MACHINE FAULT DIAGNOSIS 被引量:1
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作者 WangXinfeng QiuJing LiuGuanjun 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2005年第2期251-254,共4页
Aiming to deficiency of the filter and wrapper feature selection methods, anew method based on composite method of filter and wrapper method is proposed. First the methodfilters original features to form a feature sub... Aiming to deficiency of the filter and wrapper feature selection methods, anew method based on composite method of filter and wrapper method is proposed. First the methodfilters original features to form a feature subset which can meet classification correctness rate,then applies wrapper feature selection method select optimal feature subset. A successful techniquefor solving optimization problems is given by genetic algorithm (GA). GA is applied to the problemof optimal feature selection. The composite method saves computing time several times of the wrappermethod with holding the classification accuracy in data simulation and experiment on bearing faultfeature selection. So this method possesses excellent optimization property, can save more selectiontime, and has the characteristics of high accuracy and high efficiency. 展开更多
关键词 Feature selection Filter method Wrapper method Composite method Mutualinformation Genetic algorithm (GA)
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SOLVING COUPLED PSEUDO-PARABOLIC EQUATION USING A MODIFIED DOUBLE LAPLACE DECOMPOSITION METHOD 被引量:1
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作者 Hassan Eltayeb GADAIN 《Acta Mathematica Scientia》 SCIE CSCD 2018年第1期333-346,共14页
In this paper, the modification of double Laplace decomposition method is pro- posed for the analytical approximation solution of a coupled system of pseudo-parabolic equation with initial conditions. Some examples ar... In this paper, the modification of double Laplace decomposition method is pro- posed for the analytical approximation solution of a coupled system of pseudo-parabolic equation with initial conditions. Some examples are given to support our presented method. In addition, we prove the convergence of double Laplace transform decomposition method applied to our problems. 展开更多
关键词 double Laplace transform inverse double Laplace transform singular parabolic equation coupled pseudo-parabolic equation single Laplace transform de- composition methods
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3D Evaluation Method of Cutting Surface Topography of Carbon / Phenolic (C/Ph) Composite 被引量:4
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作者 周鹏 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2011年第3期459-463,共5页
3D evaluation method of cutting surface topography for C/Ph composites was established.The cutting surface was measured by Talyscan 150,using 3D non-contact measurement.Through the results of 2D and 3D roughness evalu... 3D evaluation method of cutting surface topography for C/Ph composites was established.The cutting surface was measured by Talyscan 150,using 3D non-contact measurement.Through the results of 2D and 3D roughness evaluating for C/Ph composite and Duralumin,the 2D evaluation method of the cutting surface topography of C/Ph composite loses a lot of information,the characteristics of the surface topography of C/Ph composite can be comprehensively and authentically evaluated only by 3D evaluation method.Furthermore,3D amplitude and spatial parameters were adopted to evaluate the surface.The results show that: the topography of the C/Ph composite is anisotropic,there are more valleys in the machined surface of C/Ph than that of duralumin,and there are not obvious feeding textures for C/Ph,which indicates the machining mechanism is different from the metal.In conclusion,the topography of the C/Ph composite cutting surface is anisotropic;the cutting surface of C/Ph composite needs 3D evaluation method. 展开更多
关键词 C/Ph composite surface topography 3D evaluation method
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Study on the Pyrolytic Carbon Generated by the Electric Heating CVD Method 被引量:1
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作者 徐先锋 欧阳甜 +1 位作者 ZENG Lingsheng CHAI Lingzhi 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2018年第2期409-413,共5页
A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon sour... A new method of fabricating C/C composite materials, namely electric heating CVD method, was used, which electrified the carbon fiber directly by using the conductivity of itself. Acetylene was used as the carbon source with nitrogen as dilution gas, and the pyrolytic carbon started to deposit on the carbon fiber surface when the deposition temperature was reached. The morphology of pyrolytic carbon was characterized by SEM, and the surface properties of carbon fibers before and after CVD were characterized by Raman spectroscopy. The experimental results show that the electric heating method is a novel method to fabricate C/C composite materials, which can form a dense C/C composite material in a short time. The order degree and the average crystallite size of the carbon fiber surface were decreased after the experiment. 展开更多
关键词 C/C composite materials electric heating method chemical vapor deposition pyrolytic carbon
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Composite penalty method of a low order anisotropic nonconforming finite element for the Stokes problem
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作者 WU Jing-zhu XING Xiu-zhi SHI Dong-yang 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2013年第1期49-56,共8页
Composite penalty method of a low order anisotropic nonconforming quadrilateral finite element for the Stokes problem is presented. This method with a large penalty parameter can achieve the same accuracy as the stand... Composite penalty method of a low order anisotropic nonconforming quadrilateral finite element for the Stokes problem is presented. This method with a large penalty parameter can achieve the same accuracy as the stand method with a small penalty parameter and the convergence rate of this method is two times as that of the standard method under the condition of the same order penalty parameter. The superconvergence for velocity is established as well. The results of this paper are also valid to the most of the known nonconforming finite element methods. 展开更多
关键词 Stokes problem composite penalty method anisotropic mesh.
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Comparison of K_(IC) Values for SiC Whisker Reinforced Ceramic Composites Obtained by Using Various Methods
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作者 Tingquan LEI Guangyong LIN +1 位作者 Shuangxi WANG and Yu ZHOU (Dept. of Metals and Technology, Harbin Institute of Technology, Harbin, 150001, China)(To whom correspondence should be addressed) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1994年第5期331-340,共10页
The fracture toughness (KIC) values determined by indentation microfracture method (IM ) for SiC whisker reinforced Al2O3 and ZrO2 based composites were calculated with different IM equations and compared with those o... The fracture toughness (KIC) values determined by indentation microfracture method (IM ) for SiC whisker reinforced Al2O3 and ZrO2 based composites were calculated with different IM equations and compared with those obtained by singte edge notched beam (SENB) technique. Experimental results show that the KIC (IM) values calculated with different equations are quite different one from another. For composites without phase transformable components the KIC (IM) and KIC (SENB) values are practically on the same level, but for composites with phase transformable components (partially stabilized zirconia) the KIC (SENB) values are always higher than KIC (IM). This is because that the IM method can not reveal sensitively the toughening effect due to dynamic t-m transformation of ZrO2 as the SENB method does. The accuracy of the IM method depends on the Suitability of the IM equations and was evaluated for the materials used in this investigation. Two new IM equations are suggested with which the KIC (IM ) values can be obtained very close to KIC (SENB) values for composites having phase transformable components. 展开更多
关键词 SiC Values for SiC Whisker Reinforced Ceramic Composites Obtained by Using Various methods Comparison of K IC
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Mean Square Stability of the Composite Milstein Method for Nonlinear Stochastic Differential Delay Equations
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作者 ZHU Xiao-lin PENG Hu 《Computer Aided Drafting,Design and Manufacturing》 2013年第4期64-70,共7页
In this paper, we construct a composite Milstein method for nonlinear stochastic differential delay equations. Then we analyze the mean square stability for this method and obtain the step size condition under which t... In this paper, we construct a composite Milstein method for nonlinear stochastic differential delay equations. Then we analyze the mean square stability for this method and obtain the step size condition under which the composite Milstein method is mean square stable. Moreover, we get the step size condition under which the composite Milstein method is global mean square stable. A nonlinear test stochastic differential delay equation is given for numerical tests. The results of numerical tests verify the theoretical results proposed. 展开更多
关键词 nonlinear stochastic differential delay equations composite Milstein method mean square stable global mean square stable
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A New Method of Hierarchical Porous HAP/Polyacrylic Acid Hydrogel Composite by in Situ Precipitation
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作者 Xin-Yu SHEN1 Zhi-Hong ZHU1 Peng WAN1 Shan-Shan LIU1Hua TONG1 ,2Δ Ji-Ming HU11(Institute ofAnalytical and Biomedical Sciences , College ofChemistry and Molecular Sciences ,Wuhan University, Wuhan430072, China)2( Center ofNano-Sciences and Nano-Technology Reseach, Wuhan University, Wuhan430072, China) 《生物医学工程学杂志》 EI CAS CSCD 北大核心 2005年第S1期57-58,共2页
关键词 HAP A New method of Hierarchical Porous HAP/Polyacrylic Acid Hydrogel Composite by in Situ Precipitation
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The Application of Flux-Form Semi-Lagrangian Transport Scheme in a Spectral Atmosphere Model 被引量:4
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作者 王晓聪 刘屹岷 +2 位作者 吴国雄 Shian-Jiann LIN 包庆 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 2013年第1期89-100,共12页
A flux-form semi-Lagrangian transport scheme (FFSL) was implemented in a spectral atmospheric GCM developed and used at IAP/LASG. Idealized numerical experiments show that the scheme is good at shape preserving with... A flux-form semi-Lagrangian transport scheme (FFSL) was implemented in a spectral atmospheric GCM developed and used at IAP/LASG. Idealized numerical experiments show that the scheme is good at shape preserving with less dissipation and dispersion, in comparison with other conventional schemes, hnportantly, FFSL can automatically maintain the positive definition of the transported tracers, which was an underlying problem in the previous spectral composite method (SCM). To comprehensively investigate the impact of FFSL on GCM results, we conducted sensitive experiments. Three main improvements resulted: first, rainfall simulation in both distribution and intensity was notably improved, which led to an improvement in precipitation frequency. Second, the dry bias in the lower troposphere was significantly reduced compared with SCM simulations. Third, according to the Taylor diagram, the FFSL scheme yields simulations that are superior to those using the SCM: a higher correlation between model output and observation data was achieved with the FFSL scheme, especially for humidity in lower troposphere. However, the moist bias in the middle and upper troposphere was more pronounced with the FFSL scheme. This bias led to an over-simulation of precipitable water in comparison with reanalysis data. Possible explanations, as well as solutions, are discussed herein. 展开更多
关键词 advection precipitation spectral composite method flux-form semi-Lagrangian Spectral Atmospheric Model of the IAP/LASG (SAMIL)
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Study on resistance coefficient in compound channels 被引量:4
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作者 Kejun Yang Shuyou Cao Xingnian Liu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2005年第4期353-361,共9页
This paper presents a further study of the Manning and Darcy-Weisbach resistance coefficients, as they play a significant role in assessing the cross-sectional mean velocity, conveyance capacity and determining the la... This paper presents a further study of the Manning and Darcy-Weisbach resistance coefficients, as they play a significant role in assessing the cross-sectional mean velocity, conveyance capacity and determining the lateral distribution of depth mean velocity and local boundary shear stress in compound channels. The relationships between the local, zonal and overall resistance coefficients, and a wide range of geometries and different roughness between the main channel and the flood plain are established by analyzing a vast amount of experimental data from a British Science and Engineering Research Council Flood Channel Facility (SERC-FCF). And the experimental results also show that the overall Darcy-Weisbach resistance coefficient for a compound channel is the function of Reynolds number, but the function relationship is different from that for a single channel. By comparing and analyzing the conventional methods with the experimental data to predict composite roughness in compound channels, it is found that these methods are not suitable for compound channels. Moreover, the reason why the conventional methods cannot assess correctly the conveyance capacity of compound channels is also analyzed in this paper. 展开更多
关键词 Resistance coefficient Compound channels Geometries ROUGHNESS Reynolds number Computational methods for composite roughness
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Synthesis,Structural Characterization and Hydrogen Storage of Nickel-containing Mesoporous MCM-48 by Electroless Plating 被引量:1
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作者 张光旭 REN Xiaocong +1 位作者 FANG Yuan CHEN Jian 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第1期64-67,共4页
Hydrogen is a promising fuel for it is clean,highly abundant and non-toxic,but on-board storage of hydrogen is still a challenge.So it is imperative to have an efficient method of hydrogen storage.The mesoporous MCM-4... Hydrogen is a promising fuel for it is clean,highly abundant and non-toxic,but on-board storage of hydrogen is still a challenge.So it is imperative to have an efficient method of hydrogen storage.The mesoporous MCM-48 especially the nickel-containing MCM-48 has great potential in hydrogen storage.MCM-48 was prepared by hydrothermal synthesis.Then electroless plating technology was used to deposit Ni on the surface of MCM-48 under ultrasonic environment.Powder X-ray diffraction(XRD),transmission electron microscopy(TEM),and N2 adsorption-desorption were employed to investigate the pore structure properties.The results showed that all the samples had Ia3 d cubic structure and pore channels were highly ordered.Hydrogen adsorption studies showed that the MCM-48 after nickel plating adsorbed nearly twice the amount of hydrogen than pure MCM-48 at 2.0 MPa,263 K.So we believe that a small amount of Ni can improve the capacity of hydrogen adsorption of MCM-48 efficiently. 展开更多
关键词 MCM-48 electroless Ni-plating ultrasonic method metallic composites hydrogen storage
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Enhancement of current density using effective membranes electrode assemblies for water electrolyser system 被引量:1
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作者 Swaminathan Seetharaman Subash Chandrabose Raghu Kambiz Ansari Mahabadi 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2016年第1期77-84,共8页
The goal of this study was to develop and design a composite proton exchange membrane(PEM) and membrane electrode assembly(MEA) that are suitable for the PEM based water electrolysis system. In particular,it focus... The goal of this study was to develop and design a composite proton exchange membrane(PEM) and membrane electrode assembly(MEA) that are suitable for the PEM based water electrolysis system. In particular,it focuses on the development of sulphonated polyether ether ketone(SPEEK) based membranes and caesium salt of silico-tungstic acid(Cs Si WA) matrix compared with one of the transition metal oxides such as titanium dioxide(TiO2), silicon dioxide(SiO2) and zirconium dioxide(ZrO2). The resultant membranes have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, ion exchange capacity(IEC), water uptake and atomic force microscopy. Comparative studies on the performance of MEAs were also conducted utilizing impregnation-reduction and conventional brush coating methods. The PEM electrolysis performance of SPEEK-Cs Si WA-ZrO2 composite membrane was more superior than that of other membranes involved in this study. Electrochemical characterization shows that a maximum current density of 1.4 A/cm^2 was achieved at 60 °C, explained by an increased concentration of protonic sites available at the interface. 展开更多
关键词 Composite membrane Membrane electrode assembly Impregnation reduction method Brush coating method Electrolysis
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Impact of Dynamic and Thermal Forcing on the Intensity Evolution of the Vortices over the Tibetan Plateau in Boreal Summer
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作者 高媛 姚秀萍 《Journal of Tropical Meteorology》 SCIE 2020年第2期239-252,共14页
The Tibetan Plateau Vortex(TPV)is one of the main weather systems causing heavy rainfall over the Tibetan Plateau in boreal summer.Based on the second Modern-Era Retrospective Analysis for Research and Applications(ME... The Tibetan Plateau Vortex(TPV)is one of the main weather systems causing heavy rainfall over the Tibetan Plateau in boreal summer.Based on the second Modern-Era Retrospective Analysis for Research and Applications(MERRA-2)reanalysis datasets provided by the National Aeronautics and Space Administration(NASA),8 cases of TPV over the Tibetan Plateau generated in June-August with a lifetime of 42 hours are composited and analyzed to reveal the impact of dynamic and thermal forcing on the intensity evolution of TPVs.The results are as follows.(1)The TPVs appear obviously at 500 h Pa and the TPVs intensity(TPVI)shows an obvious diurnal variation with the strongest at 00 LT and the weakest at 12 LT(LT=UTC+6 h).(2)A strong South Asia High at 200 h Pa as well as a shrunken Western Pacific Subtropical High at 500 h Pa provide favorable conditions for the TPVI increasing.(3)The vorticity budget reveals that the divergence is indicative of the variation of the TPVI.The TPVI decreases when the convergence center at500 h Pa and the divergence center at 200 h Pa lie in the east of the TPVs center and increases when both centers coincide with the TPVs center.(4)Potential vorticity(PV)increases with the enhancement of the TPVI.The PV budget shows that the variation of the TPVI is closely related to the diabatic heating over the Tibetan Plateau.The increased sensible heating and radiative heating in the boundary layer intensify the ascent and latent heating release.When the diabatic heating center rises to 400 h Pa,it facilitates the development of the TPVs. 展开更多
关键词 Tibetan Plateau Vortex INTENSITY dynamic composite method diabatic heating
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Synthesis and Characterization of Polyaniline/MgTiO_(3) Composite with Excellent Thermal and Electrochemical Performance
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作者 晋亚周 XING Weiwei +5 位作者 ZHAO Siyu GU Xiaojie CHI Liping YUAN Meng XU Fen 王韶旭 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2021年第5期730-736,共7页
This article explores the effects of doping ferroelectric materials MgTiO_(3) with different proportions on the properties of polyaniline(PANI).PANI/MgTiO_(3) composites were prepared by in-situ composite method.Fouri... This article explores the effects of doping ferroelectric materials MgTiO_(3) with different proportions on the properties of polyaniline(PANI).PANI/MgTiO_(3) composites were prepared by in-situ composite method.Fourier transform infrared spectroscopy(FTIR)and X-ray diffraction(XRD)were used to characterize the structure of the composites.Scanning electron microscope(SEM)was used to characterize the morphology of the composites.The thermal stability of the composites was investigated by thermogravimetry(TG)and derivative thermogravimetry(DTG).Electrochemical methods(cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS),and constant current charge-discharge test)were used to compare and analyze the electrochemical performance of the composites.TG-DTG analysis and electrochemical experiments all show that the thermal stability and electrochemical properties of the PANI/MgTiO_(3) composite with a mass ratio of 82/18(w/w)are the best.The results indicate that there is a synergistic effect between PANI and MgTiO_(3),which improves the performances of the PANI when the appropriate amount of MgTiO_(3) is added. 展开更多
关键词 PANI/MgTiO_(3)composites in-situ composite method thermal stability electrochemical performance
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Microwave absorption properties of Ag naowires/carbon black composites
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作者 黄海龙 夏辉 +2 位作者 郭智博 陈羽 李宏建 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第2期349-356,共8页
The composite that can absorb the high-performance electromagnetic(EM) wave is constructed into a sandwiched structure composed of carbon black(CB)/ethylene-vinyl acetate(EVA) and Ag naowires(Ag NWs). The Ag N... The composite that can absorb the high-performance electromagnetic(EM) wave is constructed into a sandwiched structure composed of carbon black(CB)/ethylene-vinyl acetate(EVA) and Ag naowires(Ag NWs). The Ag NWs sandwiched between two CB/EVA layers are used to improve the absorption properties of composite. The effects of EVA-to-CB weight ratio, concentration and diameter of Ag NWs with a thickness of 0.4 mm on microwave absorption are investigated.The results indicate that for an EVA-to-CB weight ratio of 1:3, Ag NW concentration of 1.0 mg/100 m L, and average diameter of 56 nm, the reflection loss(RL) of the composite is below-10 d B in a frequency range of 9.3 Ghz–18.0 GHz, with the minimum values of-40.0 d B and-25.6 d B at 13.5 GHz and 15.3 GHz, respectively. A finite element method(FEM)is used for calculating the RL of the composite. The calculated results are in agreement with the experimental data. 展开更多
关键词 microwave absorption sliver nanowires finite element method polymer-based composites
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Calibration of Discrete Element Heat Transfer Parameters by Central Composite Design 被引量:1
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作者 Zongquan DENG Jinsheng CUI +1 位作者 Xuyan HOU Shengyuan JIANG 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第2期419-427,共9页
The efficiency and precision of parameter calibration in discrete element method (DEM) are not satisfactory, and parameter calibration for granular heat transfer is rarely involved. Accordingly, parameter calibratio... The efficiency and precision of parameter calibration in discrete element method (DEM) are not satisfactory, and parameter calibration for granular heat transfer is rarely involved. Accordingly, parameter calibration for granular heat transfer with the DEM is studied. The heat transfer in granular assemblies is simulated with DEM, and the effective thermal conductivity (ETC) of these granular assemblies is measured with the transient method in simulations. The measurement testbed is designed to test the ETC of the granular assemblies under normal pressure and a vacuum based on the steady method. Central composite design (CCD) is used to simulate the impact of the DEM parameters on the ETC of granular assemblies, and the heat transfer parameters are calibrated and compared with experimental data. The results show that, within the scope of the considered parameters, the ETC of the granular assemblies increases with an increasing particle thermal conductivity and decreases with an increasing particle shear modulus and particle diameter. The particle thermal conductivity has the greatest impact on the ETC of granular assemblies followed by the particle shear modulus and then the particle diameter. The calibration results show good agreement with the experimental results. The error is less than 4%, which is within a reasonable range for the scope of the CCD parameters. The proposed research provides high efficiency and high accuracy parameter calibration for granular heat transfer in DEM. 展开更多
关键词 Granular assembly · Parameter calibration · Effective thermal conductivity (ETC) · Discrete element method (DEM) · Central composite design (CCD) · Vacuum
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Synthesis and Tribological Properties of Copper-alumina Nanocomposites Prepared by Coprecipitation Technique
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作者 符学龙 HU Yubing 陶杰 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2016年第5期1123-1130,共8页
The objective of this work is to study the synthesis of copper-alumina nanocomposites using the coprecipitation process and hot-pressing method, and investigate their mechanical properties. The effects of calcination ... The objective of this work is to study the synthesis of copper-alumina nanocomposites using the coprecipitation process and hot-pressing method, and investigate their mechanical properties. The effects of calcination temperature on the average size of composite particles and chemical composition after calcination were also analyzed. The sintering parameters including sintering temperature, hot pressure and packing time were optimized to fabricate the alumina nanoparticles reinforced copper matrix composites(CMCs). The density, microhardness and tribological properties of the CMCs reinforced with 1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt% of alumina nanoparticles were investigated correspondingly. The results showed that the optimum preparation parameters for the CMCs were 900 ℃ of hot pressing temperature, 27.5 MPa of hot pressure and 2 hrs of packing time. The CMC reinforced with 2 wt% of alumina nanoparticles had the lowest wear rate, with the relative wear resistance of 3.13. 展开更多
关键词 copper matrix composites alumina nanoparticles wear rate coprecipitation method
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