作者： Zhang, Junhui;Peng, Junhui*;Liu, Weizheng;Lu, Weihua

期刊： Road Materials and Pavement Design,2021年22(3):703-715 ISSN：1468-0629

通讯作者： Peng, Junhui

作者机构： [Peng, Junhui; Zhang, Junhui] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha, Hunan, Peoples R China.;[Liu, Weizheng] Cent South Univ, Sch Civil Engn, Changsha, Hunan, Peoples R China.;[Lu, Weihua] Nanjing Forestry Univ, Sch Civil Engn, Nanjing, Jiangsu, Peoples R China.

通讯机构： [Peng, Junhui] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha, Hunan, Peoples R China.

关键词： resilient modulus;prediction model;relative compaction;matric suction;subgrade soils

摘要： The resilient modulus has been used to characterise the stress-strain non-linear behaviour of subgrade soils and is an important parameter for pavement design and analysis. This study aims at developing an accurate and efficient methodology to estimate the resilient modulus of subgrade soils. Therefore, repeated load triaxial tests were carried out in this study. The soil matric suction was measured by the pressure plate test and the soil-water characteristic curve (SWCC) was described using the Fredlund & Xing model. Then, the influence of stress state, matric suction and relative compaction on the resilient modulus were analysed. Subsequently, a new resilient modulus model was proposed to incorporate the relative compaction and matric suction in addition to the stress state. The new model matched 7 sets of experimental data well and the coefficients of determination were high, which indicates that this new model is reasonable and widely applicable. Finally, the correlations between the basic properties variables of soil samples and the regression coefficients of the new model were established.

语种： 英文

作者： Zhao, Liang*;Zhou, Hongfang;Yin, Yanshan;Lu, Qian;Zhang, Jun

期刊： Energy Sources,2020年42(10):1286-1298 ISSN：0090-8312

通讯作者： Zhao, Liang

作者机构： [Zhao, Liang; Zhou, Hongfang] Nanjing Forestry Univ, Coll Mat Sci & Engn, Nanjing 210037, Jiangsu, Peoples R China.;[Yin, Yanshan] Changsha Univ Sci & Technol, Key Lab Efficient & Clean Energy Utilizat, Educ Dept Hunan Prov, Changsha, Hunan, Peoples R China.;[Lu, Qian; Zhang, Jun] Southeast Univ, Key Lab Energy Thermal Convers & Control, Minist Educ, Nanjing, Jiangsu, Peoples R China.

通讯机构： [Zhao, Liang] N;Nanjing Forestry Univ, Coll Mat Sci & Engn, Nanjing 210037, Jiangsu, Peoples R China.

关键词： Potassium carbonate;acetaldehyde;gasification;supercritical water;lumped kinetics

摘要： Acetaldehyde is a key intermediate to explore the biomass gasification process in supercritical water. To investigate the effects of potassium carbonate on acetaldehyde gasification in supercritical water at different temperatures (500 similar to 600 degrees C), pressures (22.5 similar to 27 MPa), residence time (6 similar to 12 s) and K2CO3 concentrations (0 similar to 2 wt.%), the experiments using the continuous reactor and the kinetics analysis using the lumped kinetic model were carried out, respectively. The experimental results showed that the operating parameters affected the yields of gaseous products during the acetaldehyde gasification in supercritical water, which were on the order of temperature>residence time>pressure. Effects of K2CO3 on the gaseous products were highly related to the temperatures. At the high temperature of 550 similar to 600 degrees C, K2CO3 significantly promoted the gasification efficiency and yields of H-2, CO2, CH4, and C3H6, while reduced the yield of CO. At the low temperature of 500 similar to 525 degrees C, K2CO3 obviously inhibited the yields of H-2 and CH4. Besides, with the increasing pressures from 22.5 MPa to 27 MPa, the effects of K2CO3 kept in the similar level. In addition, with the increasing residence time from 6 s to 12 s, the increased K2CO3 concentrations improved acetaldehyde gasification. The lumped kinetic results indicated that the effects of K2CO3 on main gaseous products were explained by promoting the direct decompositions of acetaldehyde/intermediates and methanation reaction (CO+3H(2)-> CH4+H2O), while inhibiting the water gas reverse reaction (CO+H2O <- CO2+H-2). Moreover, with the increasing K2CO3 concentration, the value of k(total) generally improved. Higher K2CO3 concentration facilitated the acetaldehyde decomposition in supercritical water.

语种： 英文

作者： Zhang, Junhui*;Peng, Junhui;Zheng, Jianlong;Yao, Yongsheng

期刊： Road Materials and Pavement Design,2020年21(1):262-275 ISSN：1468-0629

通讯作者： Zhang, Junhui

作者机构： [Peng, Junhui; Yao, Yongsheng; Zhang, Junhui; Zheng, Jianlong] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha, Hunan, Peoples R China.

通讯机构： [Zhang, Junhui] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha, Hunan, Peoples R China.

关键词： resilient modulus;prediction model;soil suction;bulk stress;compacted clays

摘要： In order to predict the resilient modulus of compacted clays, the material indicator tests, repeated load triaxial test, and pressure plate test for compacted clays from South China were carried out. The soil–water characteristic curve (SWCC) was described using the Fredlund and Xing’s model. And a logarithmic function between the soil suction and resilient modulus was built. Then, a new variable named the minimum bulk stress was defined to separate the shear effect of soil samples from the bulk stress, which avoids the bulk stress reflects two contrary effects, namely hardening effect and softening effect. Subsequently, the influences of the degree of compaction, soil suction, minimum bulk stress, and octahedral shear stress on the resilient modulus were analysed. In the following, a new resilient modulus prediction model of compacted clays, which took the soil suction, minimum bulk stress, and octahedral shear stress as the model variables, was developed and verified using the data of different cohesive soils from this study and existing literatures. The results show that the new model matched these data well and have a high prediction accuracy, which indicates that this new model is reasonable and widely applicable.

语种： 英文

作者： Zhao, Biao*;Li, Yang;Guo, Xiaoqin;Zhang, Rui*;Zhang, Jiaoxia;...

期刊： Ceramics International,2019年45(18):24474-24486 ISSN：0272-8842

通讯作者： Zhao, Biao;Zhang, Rui;Guo, Zhanhu;Fan, Jincheng

作者机构： [Guo, Xiaoqin; Zhao, Biao; Zhang, Rui] Zhengzhou Univ Aeronaut, Sch Mat Sci & Engn, Henan Key Lab Aeronaut Mat & Applicat Technol, Zhengzhou 450046, Henan, Peoples R China.;[Zhang, Rui; Li, Yang] Zhengzhou Univ, Sch Mat Sci & Engn, Zhengzhou 450001, Henan, Peoples R China.;[Zhang, Jiaoxia; Ding, Tao; Guo, Zhanhu] Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37934 USA.;[Zhang, Jiaoxia] Jiangsu Univ Sci & Technol, Sch Mat Sci & Engn, Zhenjiang 212003, Jiangsu, Peoples R China.;[Hou, Hua] North Univ China, Sch Mat Sci & Engn, Taiyuan 030051, Shanxi, Peoples R China.

通讯机构： [Zhao, B; Zhang, R] Z;[Guo, Zhanhu] U;[Fan, Jincheng] C;Zhengzhou Univ Aeronaut, Sch Mat Sci & Engn, Henan Key Lab Aeronaut Mat & Applicat Technol, Zhengzhou 450046, Henan, Peoples R China.;Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37934 USA.

关键词： NiO/Carbon;Ni/NiO/Carbon;Dual-configuration;Microwave absorption;Impedance match

摘要： Both NiO-carbon and Ni/NiO-carbon nanocomposites with a dual-configuration were successfully obtained via annealing nickel-carbon precursor under air and N2, respectively. For the NiO-carbon composites, the dual configurations were NiO nanoparticles incorporated in porous flower-like carbon materials and NiO nanoparticles anchored porous carbon microspheres. In the case of Ni/NiO-carbon composites, the dual configurations consisted of Ni/NiO nanoparticles distributed in the carbon flowers and Ni/NiO nanoparticles anchored on the porous carbon microspheres. Amazingly, an ultra-low amount (such as 2 wt%) of the NiO-carbon and Ni/NiO-carbon composites was introduced into the polyvinylidene fluoride (PVDF), the nanocomposites exhibited superior microwave absorption properties. The enhanced microwave absorption ability originated from the synergism consisting of dipole polarization, interfacial polarization, magnetic loss including natural resonance and exchange resonance, as well as dual-configuration contribution (impedance match, point discharge, multiple reflections and scattering). These PVDF nanocomposites filled with dual-configurations of NiO-carbon and Ni/NiO-carbon have been highlighted to be more competitive microwave absorbers in terms of lightweight, strong absorption and ultra-low filler amount. © 2019 Elsevier Ltd and Techna Group S.r.l.

语种： 英文

作者： Wu, Honglin*;Zhao, Shuzhen;Zhang, Jianming;Lu, Chaoquan

期刊： IEEE ACCESS,2019年7:46562-46574 ISSN：2169-3536

通讯作者： Wu, Honglin

作者机构： [Wu, Honglin] Changsha Univ Sci & Technol, Hunan Prov Key Lab Intelligent Proc Big Data Tran, Changsha 410114, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Sch Comp & Commun Engn, Changsha 410114, Hunan, Peoples R China.

通讯机构： [Wu, Honglin] C;Changsha Univ Sci & Technol, Hunan Prov Key Lab Intelligent Proc Big Data Tran, Changsha 410114, Hunan, Peoples R China.

关键词： convolutional sparse representation (CSR);learned iterative shrinkage and thresholding algorithm (LISTA);Remote sensing fusion;super-resolution

摘要： In remote sensing, it is quite necessary to fuse spectral information of low-resolution multispectral (LRMS) images and spatial information of panchromatic (PAN) images for obtaining high-resolution multispectral (HRMS) images. In this paper, an effective fusion method integrating multispectral (MS) image super-resolution and convolutional sparse representation (CSR) fusion is proposed to make full use of the spatial information of remote sensing images. First, for enhancing the spatial information of LRMS images with suitable sizes, a fast iterative image super-resolution algorithm based on the learned iterative shrinkage and thresholding algorithm (LISTA) is exploited in the first stage. It employs a feed-forward neural network to simplify the solution of sparse coefficients in the process of super-resolution. In the fusion stage, we propose a CSR-based image fusion framework, in which each MS super-resolution image and PAN image is decomposed into a basic layer and a detail layer, then we fuse the basic layers and the detail layers of the images, respectively. This hierarchical fusion strategy guarantees great performance in detail preservation. The experimental results on QuickBird, WorldView-2, and Landsat ETM+ datasets demonstrate that the proposed method outperforms other methods in terms of both objective evaluation and visual effect. © 2013 IEEE.

语种： 英文

作者： Zhang, Junhui*;Peng, Junhui;Zheng, Jianlong;Dai, Liangliang;Yao, Yongsheng

期刊： International Journal of Geomechanics,2019年19(7):04019068-null ISSN：1532-3641

通讯作者： Zhang, Junhui

作者机构： [Peng, Junhui; Yao, Yongsheng; Zhang, Junhui; Zheng, Jianlong] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Sci & Technol Innovat Platform, Changsha 410114, Hunan, Peoples R China.;[Dai, Liangliang] PE Jiaxing Highway Adm, Hangzhou 314000, Zhejiang, Peoples R China.

通讯机构： [Zhang, Junhui] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Sci & Technol Innovat Platform, Changsha 410114, Hunan, Peoples R China.

关键词： Compacted cohesive soils;Matric suction;Prediction model;Resilient modulus;Triaxial test

摘要： The resilient modulus has been used to characterize the stress-strain nonlinear behavior of subgrade soils and is the primary property needed for pavement design and analysis. The degrees of stress and moisture content have a significant impact on the resilient modulus of compacted cohesive soils. Due to the hot, humid climate in South China, the moisture content in embankments will increase gradually from the optimum moisture content (OMC) - the design water content for embankments - to the equilibrium moisture content, which relates to soil properties and the surrounding climate. In this process, the resilient modulus of embankments will obviously decrease. In order to predict the resilient modulus of typical compacted cohesive soils in South China, repeated triaxial tests were carried out in this study. The soil matric suction was measured by the pressure plate test and the soil-water characteristic curve (SWCC) was described using the Van Genuchten model with a relatively high coefficient of determination. Then, the effect of the moisture content, degree of compaction, and stress state including the deviator stress, confining pressure, and octahedral shear stress to the resilient modulus were analyzed. In addition, a logarithmic function was utilized to build the relationship between the matric suction and resilient modulus. Subsequently, a new resilient modulus estimation model of compacted soils in South China, which took the bulk stress, octahedral shear, and matric suction as the model variables, was developed and verified using the data of different cohesive soils from different studies. The results show that the new model matches their data well, and the coefficients of determination are high, which indicates that this new model is reasonable and widely applicable. Finally, the correlations between the physical parameters of soil samples, such as the liquid limit, dry density, the maximum dry density, plasticity index, percentage passing through a 0.075-mm sieve, and the regression coefficients of the new model, were established. The resilient modulus can be predicted much more easily with these physical parameters of compacted cohesive soils rather than conducting triaxial tests. © 2019 American Society of Civil Engineers.

语种： 英文

作者： Li, Jue;Zhang, Junhui*;Qian, Guoping;Zheng, Jianlong;Zhang, Yuqing

期刊： Journal of Materials in Civil Engineering,2019年31(3):04019004-null ISSN：0899-1561

通讯作者： Zhang, Junhui

作者机构： [Zhang, Junhui; Qian, Guoping; Li, Jue; Zheng, Jianlong] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410205, Hunan, Peoples R China.;[Zhang, Yuqing] Aston Univ, Sch Engn & Appl Sci, Aston Inst Mat Res, Birmingham B4 7ET, W Midlands, England.

通讯机构： [Zhang, Junhui] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410205, Hunan, Peoples R China.

关键词： Asphalt mixtures;Irregular aggregates;Three-dimensional simulation;Discrete-element method;Parameterized shape

摘要： Aggregate occupies at least three-quarters of the volume of asphalt mixture and can significantly affect the performance of pavement. The geometrical morphology influences the slippage and interlock among aggregates for resisting and distributing applied loads. In recent years, the discrete-element method (DEM) has been employed for simulation of asphalt mixture structure. This paper introduces an approach for simulation of aggregate and asphalt mixtures using parameterized shape and size gradation. Both the plane geometry factor (PGF) and the section aspect ratio (SAR) were employed to describe the three-dimensional (3D) geometric characteristics of aggregates. A numerical technique of aggregate models was implemented with probabilistic parameters depending on statistical results of PGFs and SARs. The 3D numerical model of asphalt mixtures was assembled with three different components, and was validated by uniaxial compression tests via comparison with the laboratory result. It was found that the PGF and SAR are appropriate to describe the three-dimensional features of aggregate shapes, because a simplified space object can be described by a two-dimensional (2D) graphical projection and a vector scalar corresponding to the space vector. Probability distribution curves of PGFs and SARs between coarse aggregates were in concordance with the Gauss-type function, because their correlation coefficients were all greater than 95%. It was verified that the developed clumping algorithm of aggregates was reasonable in terms of the shape and size gradation. Based on the parallel-bond model and Burger's model, the results of virtual tests were in good agreement with those of laboratory uniaxial tests. The angularity (PGF) of aggregates has a beneficial effect on the strength and stability of asphalt mixtures, whereas the flat-elongated feature (SAR) has a negative effect on the strength and stability of asphalt mixtures. © 2019 American Society of Civil Engineers.

语种： 英文

作者： Huang, Yuqin;Xia, Guanglin*;Zhang, Jian;Guo, Zaiping;Yu, Xuebin*

期刊： Energy Storage Materials,2019年17:178-185 ISSN：2405-8297

通讯作者： Xia, Guanglin;Yu, Xuebin

作者机构： [Huang, Yuqin; Yu, Xuebin] Fudan Univ, Dept Mat Sci, Shanghai 200433, Peoples R China.;[Guo, Zaiping; Huang, Yuqin; Xia, Guanglin] Univ Wollongong, Inst Superconducting & Elect Mat, North Wollongong, NSW 2522, Australia.;[Zhang, Jian] Changsha Univ Sci & Technol, Hunan Prov Key Lab Safety Design & Reliabil Techn, Changsha 410114, Hunan, Peoples R China.;[Yu, Xuebin] Shanghai Innovat Inst Mat, Shanghai 200444, Peoples R China.

通讯机构： [Xia, Guanglin] U;[Yu, Xuebin] S;Univ Wollongong, Inst Superconducting & Elect Mat, North Wollongong, NSW 2522, Australia.;Shanghai Innovat Inst Mat, Shanghai 200444, Peoples R China.

关键词： Alanates;Complex hydrides;Graphene;Hydrogen storage;Thermodynamics

摘要： The practical application of sodium alanate (NaAlH4) as a hydrogen and lithium storage material has attracted intensive attention. The high energy barrier for breaking the Al-H bonds of NaAlH4, however, remains a key challenge. Here, we report that graphene could act as an effective platform to tailor the metal-hydrogen bonds of NaAlH4 through their favorable molecular interaction. Theoretical and experimental results confirm that graphene is capable of weakening the Al-H bonds of NaAlH4, thus facilitating the breaking and recombination of Al-H bonds towards advanced hydrogen and lithium storage performance. In addition, owing to this favorable interaction, a robust nanostructure composed of homogeneous NaAlH4 nanoparticles with an average size of ~12 nm encapsulated in graphene nanosheets has been developed via a facile solvent evaporation induced deposition method with a tunable loading and distribution. The synergistic effects of the favorable molecular interaction between graphene and NaAlH4 and the noticeable decrease in particle size significantly boost the hydrogen and lithium storage performances of NaAlH4. This method provides new avenues to tailoring the molecular bonds of metal hydrides for a new range of applications in various fields. © 2018

语种： 英文

作者： Gao, Guangjun;Li, Feng;He, Kan;Wang, Jiabin;Zhang, Jie*;...

期刊： Journal of Wind Engineering and Industrial Aerodynamics,2019年185:41-53 ISSN：0167-6105

通讯作者： Zhang, Jie

作者机构： [He, Kan; Li, Feng; Wang, Jiabin; Zhang, Jie; Gao, Guangjun] Cent S Univ, Key Lab Traff Safety Track, Minist Educ, Changsha 410075, Hunan, Peoples R China.;[He, Kan; Li, Feng; Wang, Jiabin; Zhang, Jie; Gao, Guangjun] Joint Int Res Lab Key Technol Rail Traff Safety, Changsha 410075, Hunan, Peoples R China.;[He, Kan; Li, Feng; Wang, Jiabin; Zhang, Jie; Gao, Guangjun] Natl & Local Joint Engn Res Ctr Safety Technol Ra, Changsha 410075, Hunan, Peoples R China.;[Miao, Xiujuan] Changsha Univ Sci & Technol, Coll Automot & Mech Engn, Changsha 410076, Hunan, Peoples R China.;[Miao, Xiujuan] Key Lab Safety Design & Reliabil Technol Engn Veh, Changsha 410076, Hunan, Peoples R China.

通讯机构： [Zhang, Jie] C;Cent S Univ, Key Lab Traff Safety Track, Minist Educ, Changsha 410075, Hunan, Peoples R China.

关键词： High-speed train;Bogie position;Aerodynamic performance;Drag reduction;RANS

摘要： As train speed increases, the aerodynamic drag reduction becomes increasingly significant. The aim of this paper is to find out appropriate bogie positions to reduce the drag of a high-speed train. In this paper, based on the three-dimensional steady incompressible Reynolds-averaged N-S equations and the Realizable k-ε two-equation turbulence model, the effects of bogie positions on the aerodynamic performance and near wake of the three-carriage high-speed train are presented. The mesh resolution and methodology are validated against wind tunnel test. The results show that the front bogie position of the head car has a significant impact on the aerodynamic performance of the head car, leading to different aerodynamic drag forces. When the bogie moves towards the rear by 1 m and 2 m, the aerodynamic drag forces of the head car reduce by 7.75% and 10.56%, and the total drag decreases by 5.57% and 6.58%, respectively. © 2018 Elsevier Ltd

语种： 英文

作者： Lu, Weihua;Miao, Linchang;Zhang, Junhui*;Zhang, Yongxing;Li, Jing

期刊： Applied Sciences-Basel,2019年9(1) ISSN：2076-3417

通讯作者： Zhang, Junhui

作者机构： [Lu, Weihua; Zhang, Yongxing] Nanjing Forestry Univ, Sch Civil Engn, Nanjing 210037, Jiangsu, Peoples R China.;[Miao, Linchang; Li, Jing] Southeast Univ, Inst Geotech Engn, Nanjing 210096, Jiangsu, Peoples R China.;[Zhang, Junhui] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410114, Hunan, Peoples R China.

通讯机构： [Zhang, Junhui] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410114, Hunan, Peoples R China.

关键词： Axial accumulative strain;Cyclic load;Damping ratio;EPS lightweight soil;Resilient modulus

摘要： To investigate the deformation and damping characteristics of cement treated and expanded polystyrene (EPS) beads mixed lightweight soils, this study conducted a series of triaxial shear tests cyclic loading for different confining pressures, cement contents, and soil categories. Through repeated loading and unloading cycles, axial accumulative strain, resilient modulus, and damping ratio versus axial total strain were analyzed and the mechanical behavior was revealed and interpreted. Results show that the resilient modulus increases with increasing confining pressure and cement content. A decreasing power function can be used to fit the relationship between the resilient modulus and the axial total strain. Although sandy lightweight specimens usually own higher resilient modulus than silty clay lightweight specimens do, the opposite was also found when the axial total strain is larger than 8% with 50 kPa confining pressure and 14% cement content. For damping ratio the EPS beads mixed lightweight soil yields a weak growth trend with increasing axial total strain and a small reduction with higher confining pressure and cement content. For more cementations, the damping ratio of the sandy lightweight soil is always smaller than the silty clay lightweight soil. Nonetheless, the differences of damping ratios that were obtained under all of the test conditions are not significant. © 2019 by the authors.

语种： 英文

作者： Zhang, Zhuangzhuang;Zhang, Jiaoxia*;Li, Shiyun;Liu, Jianping;Dong, Mengyao;...

期刊： Composites Part B: Engineering,2019年176:107338 ISSN：1359-8368

通讯作者： Zhang, Jiaoxia;Guo, Zhanhu

作者机构： [Zhang, Jiaoxia; Li, Shiyun; Liu, Jianping; Tang, Jijun; Lei, Shuya; Zhang, Zhuangzhuang] Jiangsu Univ Sci & Technol, Sch Mat Sci & Engn, Zhenjiang 212003, Jiangsu, Peoples R China.;[Dong, Mengyao; Guo, Zhanhu] Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37996 USA.;[Dong, Mengyao] Zhengzhou Univ, Natl Engn Res Ctr Adv Polymer Proc Technol, Key Lab Mat Proc & Mold, Minist Educ, Zhengzhou 450002, Henan, Peoples R China.;[Li, Yingchun] North Univ China, Sch Mat Sci & Engn, Taiyuan 030051, Shanxi, Peoples R China.;[Lu, Na] Purdue Univ, Birck Nanotechnol Ctr, Sch Mat Engn, Lyles Sch Civil Engn, W Lafayette, IN 47906 USA.

通讯机构： [Zhang, Jiaoxia] J;[Guo, Zhanhu] U;Jiangsu Univ Sci & Technol, Sch Mat Sci & Engn, Zhenjiang 212003, Jiangsu, Peoples R China.;Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37996 USA.

关键词： Graphene;High-permittivity;Liquid crystal;Polymer-matrix composites

摘要： Graphene can form a liquid crystal phase due to its anisotropic flake characteristics, it shows great potential in the field of high dielectric composites. In this paper, the graphene oxide sheets are grafted onto copolymer to uniformly disperse and maintain the liquid crystal state in a non-polar solvent, then the modified graphene oxide liquid crystal is transferred to polydimethylsiloxane. Graphene/polydimethylsiloxane nanocomposites are obtained by high temperature reduction and curing reactions. When the filler content is 4 wt%, the permittivity increases by 800% compared to pure polydimethylsiloxane. Therefore, graphene liquid crystal can significantly improve the dielectric properties of the nanocomposites than ordinary graphene, which provides a new method for preparing high dielectric properties composites. © 2019 Elsevier Ltd

语种： 英文

作者： Ma, Lichun*;Zhu, Yingying;Feng, Peifeng;Song, Guojun;Huang, Yudong;...

期刊： Composites Part B: Engineering,2019年176:107078 ISSN：1359-8368

通讯作者： Ma, Lichun;Liu, Hu

作者机构： [Zhu, Yingying; Ma, Lichun; Feng, Peifeng; Song, Guojun] Qingdao Univ, Inst Polymer Mat, Coll Chem & Chem Engn, Qingdao 266071, Shandong, Peoples R China.;[Huang, Yudong] Harbin Inst Technol, Sch Chem Engn & Technol, Harbin 150001, Heilongjiang, Peoples R China.;[Liu, Hu] Zhengzhou Univ, Minist Educ, Natl Engn Res Ctr Adv Polymer Proc Technol, Key Lab Mat Proc & Mold, Zhengzhou 450002, Henan, Peoples R China.;[Zhang, Jiaoxia] Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37996 USA.;[Zhang, Jiaoxia] Jiangsu Univ Sci & Technol, Sch Mat Sci & Engn, Zhanjiang 212003, Peoples R China.

通讯机构： [Ma, Lichun] Q;[Liu, Hu] Z;Qingdao Univ, Inst Polymer Mat, Coll Chem & Chem Engn, Qingdao 266071, Shandong, Peoples R China.;Zhengzhou Univ, Minist Educ, Natl Engn Res Ctr Adv Polymer Proc Technol, Key Lab Mat Proc & Mold, Zhengzhou 450002, Henan, Peoples R China.

关键词： Carbon fibers;Graphene oxide;Interfacial strength;Polymer-matrix composites

摘要： To improve the dispersion of graphene oxide (GO) nanosheets in sizing agent and to enhance the interfacial adhesion between GO and epoxy, GO nanosheets were chemically modified with cyanuric chloride (TCT) and diethylenetriamine (DETA). The functionalized GO (i.e. GO-TCT-DETA) with different contents was introduced into the carbon fiber (CF) interface by sizing process. The uniform distribution of GO sheets on CF surface and the enhancement of surface roughness were obtained. Moreover, significant enhancements (i.e., 104.2%, 100.2%, and 78.3%) of interfacial shear strength (IFSS), interlaminar shear strength (ILSS), and flexural properties were achieved in the composites with only 1.0 wt% GO-TCT-DETA sheets introduced in the fiber sizing. The GO-TCT-DETA in the interface region enhanced the stress being transferred effectively and the local stress concentrations being relieved. This study indicates that the utilization of functionalized GO is one of the alternative approaches for controlling the fiber-matrix interface and improving the mechanical properties of CF epoxy composites. © 2019 Elsevier Ltd

语种： 英文

作者： Xing, Xuemin*;Chang, Hsing-Chung;Chen, Lifu;Zhang, Junhui;Yuan, Zhihui;...

期刊： Remote Sensing,2019年11(4):429 ISSN：2072-4292

通讯作者： Xing, Xuemin

作者机构： [Xing, Xuemin; Zhang, Junhui; Shi, Zhenning] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410014, Hunan, Peoples R China.;[Xing, Xuemin; Chang, Hsing-Chung] Macquarie Univ, Dept Environm Sci, Sydney, NSW 2109, Australia.;[Yuan, Zhihui; Chen, Lifu] Changsha Univ Sci & Technol, Sch Elect & Informat Engn, Changsha 410014, Hunan, Peoples R China.

通讯机构： [Xing, Xuemin] C;[Xing, Xuemin] M;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410014, Hunan, Peoples R China.;Macquarie Univ, Dept Environm Sci, Sydney, NSW 2109, Australia.

关键词： SBAS InSAR;deformation;soft clay subgrade;seasonal variation

摘要： Monitoring surface movement near highways over soft clay subgrades is fundamental for understanding the dynamics of the settlement process and preventing hazards. Earlier studies have demonstrated the accuracy and cost-effectiveness of using time series radar interferometry (InSAR) technique to measure the ground deformation. However, the accuracy of the advanced differential InSAR techniques, including short baseline subset (SBAS) InSAR, is limited by the temporal deformation models used. In this study, a comparison of four widely used time series deformation models in InSAR, namely Multi Velocity Model (MVM), Permanent Velocity Model (PVM), Seasonal Model (SM) and Cubic Polynomial Model (CPM), was conducted to measure the long-term ground deformation after the construction of road embankment over soft clay subgrade. SBAS-InSAR technique with TerraSAR-X satellite imagery were conducted to generate the time series deformation data over the studied highway. In the experiments, three accuracy indices were applied to show the residual phase, mean temporal coherence and the RMS of high-pass deformation, respectively. In addition, the derived time series deformation maps of the highway based on the four selected models and 17 TerraSAR-X images acquired from June 2014 to November 2015 were compared. The leveling data was also used to validate the experimental results. Our results suggested the Seasonal Model is the most suitable model for the selected study site. Consequently, we analyzed two bridges in detail and three single points distributed near the highway. Compared with the ground leveling deformation measurements and results of other models, SM showed better consistency, with the accuracy of deformation to be ±7 mm. © 2019 by the authors.

语种： 英文

作者： Guo, Zhongzhao;Ma, Yafei*;Wang, Lei;Zhang, Jianren

期刊： Engineering Failure Analysis,2019年105:883-895 ISSN：1350-6307

通讯作者： Ma, Yafei

作者机构： [Ma, Yafei; Wang, Lei; Zhang, Jianren; Guo, Zhongzhao] Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Hunan, Peoples R China.

通讯机构： [Ma, Yafei] C;Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Hunan, Peoples R China.

关键词： Bridge engineering;Fatigue crack growth;Pitting corrosion;Probabilistic method;Stress concentration

摘要： Corrosion accelerates the fatigue damage accumulation and decreases the fatigue life of reinforced concrete bridges. A critical issue in the corrosion-fatigue life prediction is to deal with the relationship between fatigue crack and corrosion propagation. This paper proposes two modelling methods for fatigue life prediction of reinforced concrete bridges subjected to coupled corrosion-fatigue effect: model I considers the corrosion pit as a notch and model II treats the corrosion pit as a surface crack. The chloride ingress, cyclic load, corrosion pit growth, fatigue crack growth and concrete severe cracking are systematically considered. Following that, a probabilistic analysis is also performed to include various uncertainties in the two models, and the effects of environment aggressiveness level and traffic frequency on the prediction results are investigated. The results show that corrosion pit-induced stress concentration has a significant effect on the fatigue behavior, and modelling the corrosion pit as a notch is the preferred method for theoretical prediction. For the extreme aggressiveness environment and low traffic frequency conditions, considering the corrosion pit as a crack is an alternative modelling method for the fast assessment of aging reinforced concrete bridges due to its simplicity. © 2019 Elsevier Ltd

语种： 英文

作者： Li, Yujun*;Xu, Zhao;Xiong, Liansong;Song, Guobing;Zhang, Jianliang;...

期刊： Renewable Energy,2019年132:846-860 ISSN：0960-1481

通讯作者： Li, Yujun

作者机构： [Li, Yujun; Song, Guobing] Xi An Jiao Tong Univ, Sch Elect Engn, Xian, Shaanxi, Peoples R China.;[Li, Yujun; Xiong, Liansong; Xu, Zhao] Hong Kong Polytech Univ, Dept Elect Engn, Hong Kong, Hong Kong, Peoples R China.;[Xiong, Liansong] Nanjing Inst Technol, Sch Automat, Nanjing, Jiangsu, Peoples R China.;[Qi, Donglian; Zhang, Jianliang] Zhejiang Univ, Sch Elect Engn, Hangzhou, Zhejiang, Peoples R China.;[Yang, Hongming] Changsha Univ Sci & Technol, Sch Elect & Informat Engn, Changsha, Hunan, Peoples R China.

通讯机构： [Li, Yujun] X;Xi An Jiao Tong Univ, Sch Elect Engn, Xian, Shaanxi, Peoples R China.

关键词： Power system dispatch;Wind generator (WG);Kinetic energy (KE);Photovoltaic (PV);Power sharing control (PSC)

摘要： Traditionally, wind power and solar photovoltaic (PV) power generation is non-dispatchable and their normal operation relies on Maximum Power Point Tracking (MPPT) control. Therefore, it can be of highly disturbance to the system dispatch in particularly context of microgrids. To effectively fulfill dispatch command or market schedule, a novel cascading power sharing control (PSC) scheme is proposed to coordinate wind and solar PV power productions in microgrids while reducing the loss of renewable energy production involved. Considering different properties of wind and solar PV power generation systems, the discrepancies between dispatch command (market schedule) and actual renewable generation is firstly counterbalanced by adjusting wind power output via temperately storing or releasing kinetic energy of turbine rotors. Only when rotors of wind generator reach their limitations, should solar PVs begin to reduce their generation. The proposed PSC scheme is fully simulated in a microgrid with wind and solar PV, and the simulation results clearly indicate it can be more energy efficient than the traditional dispatch method while fulfilling the dispatch demand. (C) 2018 Elsevier Ltd. All rights reserved.

语种： 英文

作者： Yao, Hui*;Dai, Qingli;You, Zhanping*;Zhang, Jinxi;Lv, Songtao;...

期刊： Construction and Building Materials,2019年212:727-736 ISSN：0950-0618

通讯作者： Yao, Hui;You, Zhanping

作者机构： [Zhang, Jinxi; Yao, Hui] Beijing Univ Technol, Coll Metropolitan Transportat, Beijing Key Lab Traff Engn, 100 Pingleyuan, Beijing 100124, Peoples R China.;[You, Zhanping; Yao, Hui; Dai, Qingli] Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA.;[Lv, Songtao] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.;[Xiao, Xianghui] Natl Synchrotron Light Source II, Brookhaven Natl Lab, Upton, NY 11973 USA.;[Xiao, Xianghui] Argonne Natl Lab, Adv Photon Source, Upton, NY 60439 USA.

通讯机构： [Yao, Hui] B;[Yao, H; You, ZP] M;Beijing Univ Technol, Coll Metropolitan Transportat, Beijing Key Lab Traff Engn, 100 Pingleyuan, Beijing 100124, Peoples R China.;Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA.

关键词： Asphalt binder;Contact angle;Flow;Molecular Dynamics (MD)

摘要： The objectives of this study are to explore the mechanism of the self-healing or flow of asphalt binder on the surface of the aggregates and evaluate the contact angle between the asphalt binder and aggregates. The mastic samples (small size) were prepared with asphalt binder and fine aggregates of a small size (below 0.3 mm). The microscale dynamic X-ray tomography was used to observe the flow of asphalt binder in the mastic sample at 353.15 K (80 °C) using the Advanced Photon Source (APS) beamline 2-BM at Argonne National Laboratory. The activation energy for flow of the asphalt binder and the contact angle between the asphalt binder and aggregates were analyzed to explain the self-healing characteristics of the asphalt binder materials. The Molecular Dynamics (MD) method was employed to simulate the flow process of the molecules of asphalt binder at different temperatures and mimic the contact angle difference between the asphalt binder and aggregate models. Simultaneously, in the laboratory, the contact angle goniometer was selected to measure the contact angle between the asphalt binder droplet and aggregates at different temperatures. The results of tests and MD simulations show that (1) asphalt binder diffused after heating from the X-ray images, and the stages and mechanism of the flow process of asphalt binder on aggregates were investigated; (2) low contact angle was observed in the interface model of asphalt binder and aggregates at high temperatures using the MD method. The wetting condition changed from partial non-wetting to wetting after heating in the interface model; (3) contact angle results between the asphalt binder and aggregates demonstrated flow steps of the asphalt binder material. The test data was also compared with the MD simulation results at different temperatures. © 2019

语种： 英文

作者： Liang, Taixin*;Qi, Le;Ma, Zhongliang;Xiao, Zhongliang;Wang, Yang;...

期刊： Composites Part B: Engineering,2019年166:428-435 ISSN：1359-8368

通讯作者： Liang, Taixin;Lu, Na;Liu, Chuntai;Xie, Wei;Ding, Tao

作者机构： [Qi, Le; Ma, Zhongliang; Liang, Taixin] North Univ China, Sch Environm & Safety Engn, Taiyuan 030051, Shanxi, Peoples R China.;[Xiao, Zhongliang] Nanjing Univ Sci & Technol, Sch Chem Engn, Nanjing 210094, Jiangsu, Peoples R China.;[Wang, Yang; Lu, Na] Purdue Univ, Lyles Sch Civil Engn, Sch Mat Engn, Birck Nanotechnol Ctr, W Lafayette, IN 47906 USA.;[Zhang, Jiaoxia; Liu, Hu; Guo, Zhanhu] Univ Tennessee, ICL, Dept Chem & Biomol Engn, Knoxville, TN 37996 USA.;[Liu, Hu; Liu, Chuntai] Zhengzhou Univ, Key Lab Mat Proc & Mold, Minist Educ, Zhengzhou 450002, Henan, Peoples R China.

通讯机构： [Liang, Taixin] N;[Lu, Na] P;[Liu, Chuntai] Z;[Xie, Wei] C;[Ding, Tao] H

关键词： Flaky gun propellant;Thermal expansion coefficient;TMA (thermal mechanical analyzer) test;Variable burning-rate gun propellant

摘要： Improving the burning progressivity is an effective approach to improve the muzzle velocities of projectile of a gun. Composite multi-layered flaky gun propellant is a combination of a fast-burning inner layer and a slow-burning outer layer. It has an obvious burning progressivity which decreases the pressure in bore and increases the muzzle velocity, thus this characteristic is widely concerned by the research of gun propellant. The thermal expansion coefficient of composite multi-layered gun propellant has a significant influence on the combustion performance. Therefore, understanding the thermal expansion properties of the composite multi-layered gun propellant is important. In this study, the thermal expansion coefficients were measured by thermal mechanical analyzer (TMA) for a three-layered flaky gun propellant, and the influence of laminating and coating flaky gun propellant on thermal expansion coefficient was investigated. The results showed that the slow-burning layers had a higher thermal expansion coefficient than the faster-burning layers, the thermal expansion coefficient of slow-burning layers was 4–5 times bigger than that of fast-burning layers, and the order of magnitudes was 1 × 10 −5 K −1 . The laminating and coating had a great influence on the thermal expansion coefficient of flaky gun propellant, the thermal expansion coefficient of laminate sample was 10 times greater than that of the original sample, and the order of magnitudes for two layers and three layers propellant reached 1 × 10 −4 K −1 . Furthermore, the theoretical relations between the thermal expansion coefficient of axial and the thermal expansion coefficient of the fast and slow burning layer were derived. © 2019 Elsevier Ltd

语种： 英文

作者： Li, Ying;Zhang, Tong;Jiang, Bo*;Zhao, Liwei;Liu, Hu;...

期刊： Composites Science and Technology,2019年181:107689 ISSN：0266-3538

通讯作者： Jiang, Bo;Huang, Yudong;Guo, Zhanhu

作者机构： [Huang, Yudong; Li, Ying; Jiang, B; Huang, YD; Zhao, Liwei; Jiang, Bo; Zhang, Tong] Harbin Inst Technol, Sch Chem & Chem Engn, MIIT Key Lab Crit Mat Technol New Energy Convers, Harbin, Heilongjiang, Peoples R China.;[Zhang, Jiaoxia; Liu, Hu; Fan, Jincheng; Guo, Zhanhu] Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37934 USA.;[Liu, Hu] Zhengzhou Univ, Natl Engn Res Ctr Adv Polymer Proc Technol, Minist Educ, Key Lab Mat Proc & Mold, Zhengzhou 450002, Henan, Peoples R China.;[Zhang, Jiaoxia] Jiangsu Univ Sci & Technol, Sch Mat Sci & Engn, Zhenjiang 212003, Jiangsu, Peoples R China.;[Fan, Jincheng] Changsha Univ Sci & Technol, Coll Mat Sci & Engn, Changsha 410114, Hunan, Peoples R China.

通讯机构： [Jiang, B; Huang, YD] H;[Guo, Zhanhu] U;Harbin Inst Technol, Sch Chem & Chem Engn, MIIT Key Lab Crit Mat Technol New Energy Convers, Harbin, Heilongjiang, Peoples R China.;Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37934 USA.

关键词： Carbon fiber;Composite material;Interfacial property

摘要： The interfacial interaction between carbon fibers (CFs) and resin matrix is an important factor affecting mechanical performances of CF-based composites. In this work, a new approach combining electrodeposition method (EDM) and “Ag–S″ bonds was applied to fabricate functional CF-based composites while preserving the mechanical properties of CFs. Silver nanoparticles were first attached on the CF surface by EDM. Then 4-aminothiophenol or 4-mercaptobenzoic acid was linked to Ag surface by Ag–S bonds to incorporate different functional groups onto the fiber surface. The interfacial shear strength was improved pronouncedly while the tensile strength was maintained consistent. The interfacial shear strength of the CFs after functionalized was increased 21.10% and 32.04%, respectively. However, the tensile strength of them decreased no more than 3%. With improved properties, these nanocomposites have potential applications for aerospace, transportation, electronics and other fields. © 2019 Elsevier Ltd

语种： 英文

作者： Jiang, Youbao*;Peng, Suixiang;Beer, Michael;Wang, Lei;Zhang, Jianren

期刊： Advances in Structural Engineering,2019年23(1):146-159 ISSN：1369-4332

通讯作者： Jiang, Youbao

作者机构： [Jiang, Youbao; Peng, Suixiang; Wang, Lei; Zhang, Jianren] Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Hunan, Peoples R China;[Beer, Michael] Leibniz Univ Hannover, Inst Risk & Reliabil, Hannover, Germany;[Beer, Michael] Univ Liverpool, Inst Risk & Uncertainty, Liverpool, Merseyside, England

通讯机构： [Jiang, Youbao] C;Changsha Univ Sci & Technol, Sch Civil Engn, Changsha 410114, Hunan, Peoples R China.

关键词： contribution analysis;Eurocode-based design;random loads eccentricity;reinforced concrete columns;reliability evaluation;wind-dominated combination

摘要： With the capacity models in the 2004 edition of the European Committee for Standardization’s Standard Design of Concrete Structures, a more realistic limit state function is obtained for reinforced concrete columns with random loads eccentricity. Using this function, the applicability of the code-based design factors is discussed. Taking the wind-dominated combination as an example, the probabilistic distribution of loads eccentricity and the statistics of column resistance are analyzed for representative cases. The analysis indicates that the possible loads eccentricity is scattered over a large range, and the probabilistic model of column resistance varies from case to case, which is largely different from the resistance model assumed in previous reliability calibration. With Monte Carlo simulation, the column reliability and the contributions of both tension failure and compression failure to the total failure probability are calculated and obtained for different cases. The results show that the fixed loads eccentricity criterion underestimates differences in the reliability of columns for different loads eccentricity cases and overestimates the column reliability in some tension failure cases. Furthermore, it is found that the tension failure mode contributes most to the total failure probability for not only some columns designed to fail in tension failure but also for some columns designed to fail in compression failure. To attain a robust design, a group of optimum wind load factors varying with cases is recommended. The new calibration results prove that the recommended wind local factors can achieve a better goal. © The Author(s) 2019.

语种： 英文

作者： Huang, Xiaoshuai;Yin, Rui;Qian, Lei*;Zhao, Wen;Liu, Hu*;...

期刊： Ceramics International,2019年45(14):17784-17792 ISSN：0272-8842

通讯作者： Qian, Lei;Liu, Hu

作者机构： [Huang, Xiaoshuai; Yin, Rui; Qian, Lei] Shandong Univ, Shenzhen Res Inst, 19 Gaoxin South Four Rd, Shenzhen 518057, Peoples R China.;[Huang, Xiaoshuai; Yin, Rui; Qian, Lei; Zhao, Wen] Shandong Univ, Key Lab Liquid Solid Struct Evolut & Proc Mat, Minist Educ, 17923 Jingshi Rd, Jinan 250061, Shandong, Peoples R China.;[Liu, Hu; Liu, Chuntai] Zhengzhou Univ, Key Lab Mat Proc & Mold, Natl Engn Res Ctr Adv Polymer Proc Technol, Minist Educ, Zhengzhou 450002, Henan, Peoples R China.;[Fan, Jincheng] Changsha Univ Sci & Technol, Coll Mat Sci & Engn, Changsha 410114, Hunan, Peoples R China.;[Liu, Hu; Guo, Zhanhu] Univ Tennessee, Dept Chem & Biomol Engn, ICL, Knoxville, TN 37996 USA.

通讯机构： [Qian, Lei] S;[Liu, Hu] Z;Shandong Univ, Shenzhen Res Inst, 19 Gaoxin South Four Rd, Shenzhen 518057, Peoples R China.;Zhengzhou Univ, Key Lab Mat Proc & Mold, Natl Engn Res Ctr Adv Polymer Proc Technol, Minist Educ, Zhengzhou 450002, Henan, Peoples R China.

关键词： Negative permittivity;Reduced graphene oxide;Spark plasma sintering

摘要： In this study, reduced graphene oxide-alumina (RGO-Al2O3) metacomposites with tunable negative permittivity were obtained from spark plasma sintering method. Regulation of negative permittivity was realized by adjusting the sintering process conditions. The effects of sintering temperature and pressure on the dielectric properties of RGO-Al2O3 metacomposites were firstly studied in details. Interestingly, the Fano-like resonance phenomenon was observed in the RGO-Al2O3 metacomposites containing 8.91 and 15.01 vol% GO produced from 1000 °C at 50 MPa. This phenomenon was attributed to the interference of two kinds of resonances, which was different from general polarization dipole resonance. The sintering temperature regulated the permittivity via the micro-capacitance of RGO itself and the interfacial effect between RGO and Al2O3 grains. The resonance frequency was also dependent on the sintering temperature. The sintering pressure effectively controlled the value of permittivity and the resonance frequency which were influenced by the degree of GO reduction and the mutual contact between grains. With the increase of the sintering pressure, the value of permittivity increased and the resonance frequency advanced. Overall, the permittivity and the resonance frequency of the RGO-Al2O3 metacomposites were easily regulated by adjusting the sintering process conditions. © 2019 Elsevier Ltd and Techna Group S.r.l.

语种： 英文