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Chinese Journal of Polymer Science 2014年第1期32卷 92-97页

作者： Zhi Geng Song Guan He-ming jiang 高龙成 Zhi-wen Liu Lei jiang Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education School of Chemistry and Environment BeiHang University Agilent Technologies Beijing National Laboratory for Molecular Sciences (BNLMS) Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences

pH-sensitive wettability of polystyrene-b-poly（4-vinylpyridine）（PS-b-P4VP） self assembled films, exhibiting superoleophobicity under water and hydrophilicity at low pH value, and oleophobicity under water and hydrophobicity at neutral condition, has been realized. The wettability properties resulted from the surface topological and chemical transition, which were confirmed by in situ AFM measurements under water at different pH. At low pH, P4VP chains, which were confined in the hexagonal-packed nanodomains, got protonated into a swollen state, while at high pH, P4VP chains were deprotonated into a collapsed state. The reversible protonation/deprotonation procedure on the molecular scale leads to surface topological and chemical transition, thereby pH-sensitive wettability.

关键词： Block copolymer Wettability pH sensitive Self assembly.

An Internal Expansive Stress Model of Concrete under Sulfate Attack

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Acta Mechanica Solida Sinica 2016年第6期29卷 610-619页

作者： Hui Song Jiankang Chen Jinyang jiang The Faculty of Mechanical Engineering and Mechanics Ningbo University Ningbo 315211 China State Key Laboratory of Turbulence and Complex Systems Peking University Beijing 100871 China The Faculty of Civil Engineering and Architecture Nanchang Institute of Technology Nanchang 300029 China School of Materials Science and Engineering Southeast University Nanjing 211189 China

Concrete experiences expansive deformation during sulfate attack due to internal expansive stress. Sulfate ions enter concrete pores, react with the pore solution, and produce ettringite. The production of ettringite explains the internal expansive stress that reduces the durability of concrete. In this study, the model of internal expansive stress was achieved through the Eshelby＇s theory, as well as the experimental results for concrete erosion. Numerical simulation indicated that internal expansive stress is not only determined by the water-to-cement ratio of concrete and the concentration of sulfate solution, but also affected by the relaxation time of concrete.

关键词： concrete viscous internal stress model erosion micromechanics

An Adaptive Time Delay Estimator Based on ETDE Algorithm with Noisy Measurements

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Chinese Journal of Electronics 2017年第4期26卷 760-767页

作者： XIA Wei jiang Wenying ZHU Lingfeng School of Electronic Engineering University of Electronic Science and Technology of China

We address the problem of adaptive time delay estimation with noisy measurements. We develop a computationally efficient adaptive time delay estimator based on Explicit time delay estimation(ETDE) algorithm,by applying the unbiased impulse response estimation approach. In this algorithm, a weighted error function is derived, and the time delay is explicitly parameterized in the filter coefficients and iteratively updated directly by utilizing the modified error function. Simulations validate the performance of the proposed algorithm for colored input and low signal-to-noise ratio scenarios.

关键词： Adaptive filter Time delay estimate Noisy measurements Colored input

High-order implicit discontinuous Galerkin schemes for unsteady compressible Navier–Stokes equations

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Chinese Journal of Aeronautics 2014年第6期27卷 1384-1389页

作者： jiang Zhenhua Yan Chao Yu Jian School of Aeronautic Science and Engineering Beihang University

Efficient solution techniques for high-order temporal and spatial discontinuous Galerkin（DG） discretizations of the unsteady Navier–Stokes equations are developed. A fourth-order implicit Runge–Kutta（IRK） scheme is applied for the time integration and a multigrid preconditioned GMRES solver is extended to solve the nonlinear system arising from each IRK stage. Several modifications to the implicit solver have been considered to achieve the efficiency enhancement and meantime to reduce the memory requirement. A variety of time-accurate viscous flow simulations are performed to assess the resulting high-order implicit DG methods. The designed order of accuracy for temporal discretization scheme is validate and the present implicit solver shows the superior performance by allowing quite large time step to be used in solving time-implicit systems. Numerical results are in good agreement with the published data and demonstrate the potential advantages of the high-order scheme in gaining both the high accuracy and the high efficiency.

关键词： Discontinuous Galerkin scheme GMRES solver High order Implicit Runge–Kutta method Unsteady flows

Microstructural characteristics and deformation of magnesium alloy AZ31 produced by continuous variable cross-section direct extrusion

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Journal of Materials Science & Technology 2017年第6期33卷 573-579页

作者： Hongwei jiang Feng Li Xiang Zeng School of Materials Science and Engineering Harbin University of Science and Technology

Magnesium（Mg） alloy AZ31 was produced by continuous variable cross-section direct extrusion（CVCDE）to study its deformation behavior. Metallographic microscopy（OM）, transmission electron microscopy（TEM）, and scanning electron microscopy（SEM） were used to observe the variations in microstructure and fracture morphology of Mg alloy AZ31 as a function of processing methods. The results reveal that grains of Mg alloy AZ31 were refined and their microstructure was homogenized by CVCDE. The recrystallization in Mg alloy AZ31 produced by CVCDE with 2 interim dies was more complete than that produced by conventional extrusion（CE） and CVCDE with 1 interim die, and the grains were finer and more *** of the AZ31 alloy was improved. Fracture mode was evolved from a combination of ductility and brittleness to a sole ductile form. In summary, a CVCDE mold structure with 2 interim dies can improve microstructure, plasticity, and toughness of Mg alloy AZ31.

关键词： Continuous variable cross-section direct extrusion(CVCDE) Magnesium alloys Microstructural characteristics Plastic deformation

Fracture Toughnesses and Crack Growth Angles of Single-Layer Graphyne Sheets

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Acta Mechanica Solida Sinica 2019年第3期32卷 339-355页

作者： Zonghuiyi jiang Rong Lin Junhua Zhao jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Jiangnan University Wuxi 214122 China Institute of Mechanics and Advanced Materials School of Mechanical Engineering Jiangnan University Wuxi 214122 China

Recently, Shang et al.(Angew Chem Int Ed 57(3):774-778,2018) have developed a method to synthesize ultrathin (around 1.9 nm) graphyne nanosheets. We reported here the mixed-mode I-II fracture toughnesses and crack growth angles of single-layer graphyne sheets using molecular dynamics (MD) simulations and the finite element (FE) method based on the boundary layer model, respectively. The various carbon-carbon bonds of graphyne sheets in the FE method are equated with the nonlinear Timoshenko beams based on the Tersoff-Brenner potential, where all the parameters of the nonlinear beams are completely determined based on the continuum modeling. All the results from the present FE method are reasonable in comparison with those from our MD simulations using the REBO potential. The present results show that both the critical stress intensity factors (SIFs) and the crack growth angle strongly depend on the chirality and loading angle q @= 90° and #= 0° representing pure mode I and pure mode II, respectively). Meanwhile, the fracture properties of single-layer cyclicgraphene and supergraphene sheets are also studied in order to compare with those of the graphyne sheets. The critical equivalent SIFs are derived as 1.55 < *** (cyclic)< 1.95 nN A-3/2, 1.64 < *** (graphyne)< 2.64 nN A_3/<2 and 0.61 < Keq-su (super)< 2.04 nN A-3/2 in the corresponding zigzag and armchair sheets using the MD simulations, while the SIFs are 0.32 < Keq-cy (cyclic)< 0.48 nN A-3/,2, 1.96 < *** (graphyne)< 2.49 nN A-3^2 and 1.42 < Keq-su (super)< 2.95 nN A_3//2 using the FE method. These findings should be of great help for understanding the fracture properties of carbon allotropes and designing the carbon-based nanodevices.

关键词： Fracture toughness Graphyne Molecular dynamics Finite element

Effects of UV-B radiation on the growth interaction of Ulva pertusa and Alexandrium tamarense

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Journal of Environmental Sciences 2005年第4期17卷 605-610页

作者： CAIHeng-jiang TANGXue-xi ZHANGPei-yu MarineEcologyLaboratory OceanUniversityofChinaQingdao266003China MarineEcologyLaboratory OceanUniversityofChinaQingdao266003China／／DepartmentofEnvironmentalScienceandEngineeringQingdaoUniversityQingdao266071China

Enhanced UV-B(280-320 nm) radiation resulting from ozone depletion is one of global environmental problems. Not only marine organisms but also marine ecosystems can be affected by enhanced UV-B radiation. The effects of UV-B radiation on interaction of macro-algae and micro-algae were investigated using Ulva pertusa Kjellman and Alexandrium tamarense as the materials in this study. The results demonstrated that UV-B radiation could inhibit the growth of Ulva pertusa and Alexandrium tamarense when they were both mono-cultured, and the growth inhibition of algae was more significant with increasing doses of UV-B radiation. Alexandrium tamarense could inhibit the growth of Ulva pertusa in mixed culture, and the growth inhibition was more significant when increasing the initial cell density. However, Ulva pertusa could inhibit the growth of Alexandrium tamarense in early phase and stimulate the growth in latter phase when they were grown in mixed culture. Lower initial cell density(10~2 cell/ml) of Alexandrium tamarense could inhibit the growth of Ulva pertusa under UV-B radiation treatment,however, with the initial cell density increasing(10~3 and 10~4 cell/ml), the growth of Ulva pertusa was stimulated under lower dose of UV-B radiation and inhibited under higher dose of UV-B radiation by Alexandrium tamarense. Compared with that in mixed culture, Ulva pertusa showed more positive inhibition to the growth of Alexandrium tamarense under UV-B radiation treatment.

关键词： UV-B radiation mono-culture mixed culture Ulva pertusa Alexandrium tamarense growth

Thermoelectric properties of Bi0.5Sb1.4-xNaxIn0.1Te3 alloys

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Rare Metals 2019年第12期38卷 1187-1192页

作者： Yue-Zhen jiang Xing-Kai Duan School of Electronic Engineering Jiujiang UniversityJiujiang 332005China School of Mechanical and Materials Engineering Jiujiang UniversityJiujiang 332005China

The Bi(0.5)Sb(1.4-x)NaxIn(0.1)Te3(x=0.02-0.20)alloys were fabricated by high vacuum melting and hotpressing *** phase structures and morphology of the bulk samples were characterized by X-ray diffraction(XRD) and scanning electron microscope(SEM),*** of In and Na co-doping on the electrical and thermal transport properties were studied from room temperature to 500 *** coefficient of the Bi(0.5)Sb(1.5)Te3 can be enhanced by substituting Sb with In and Na at near room *** electrical conductivity of the In and Na co-doped samples is lower than that of the Bi(0.5)Sb(1.5)Te3 alloy from room temperature to 500 *** and Na co-doping of appropriate percentage optimizes the thermal conductivity of the Bi(0.5)Sb(1.5)Te3 *** minimum value of thermal conductivity of Bi(0.5)Sb(1.36)Na(0.04)In(0.1)Te3 alloy is 0.45 W·m^(-1) K^(-1) at 323 *** leads to a great improvement in the thermoelectric figure of merit(zT).The maximum zT value reaches 1.42 at 323 K.

关键词： Microstructure Co-doping Thermal conductivity Electrical properties

Pressure and velocity cross-spectrum of normal modes in low-frequency acoustic vector field of shallow water and its application

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Journal of Systems Engineering and Electronics 2015年第2期26卷 241-249页

作者： Yun Yu Qing Ling jiang Xu Naval Academy of Armament

The pressure and horizontal particle velocity combined descriptions in the very low frequency acoustic field of shallow wa- ter integrated with the concept of effective depth of Pekeris wave- guide is proposed, especially the active component of the pressure and horizontal particle velocity cross-spectrum, also called ho- rizontal complex cross acoustic intensity, when only two normal modes are trapped in the waveguide. Both the approximate theo- retic analysis and the numerical results show that the sign of the horizontal complex cross acoustic intensity active component is independent of the range when vertically deployed receiving dual sensors are placed in appropriate depths, the sum of which is equal to the waveguide effective depth, so it can be used to tell whether the sound source is near the surface or underwater; while the range rate is expected to be measured by utilizing the sign distribution characteristic of the reactive component. The further robustness analysis of the depth classification algorithm shows that the existence of shear waves in semi infinite basement and the change of acoustic velocity profiles have few effects on the application of this method, and the seabed attenuation will limit the detection range, but the algorithm still has a good robustness in the valid detection range.

关键词： low frequency acoustic vector field effective depth complex cross acoustic intensity active component target depth classificatio

Stress corrosion cracking of magnesium alloys:A review

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Journal of Magnesium and Alloys 2023年第6期11卷 1906-1930页

作者： Jiahao jiang Xue Geng Xiaobo Zhang School of Materials Science and Engineering Nanjing Institute of TechnologyNanjing 211167China jiangsu Key Laboratory of Advanced Structural Materials and Application Technology Nanjing 211167China

Magnesium(Mg)alloys have been widely used in automobile,aviation,computer,and other fields due to their lightweight,high specific strength and stiffness,low pollution,and good electromagnetic shielding ***,the chemical stability of Mg alloys is poor,especially in the corrosive medium environment with high stress corrosion sensitivity,which causes sudden damage to structural components and restricts their application *** recent years,owing to the increasing failure rate of engineering structures caused by stress corrosion of Mg alloys,it has become necessary to understand and pay more attention to the stress corrosion cracking(SCC)behavior of Mg *** this paper,the SCC mechanisms and test methods of Mg alloys have been *** recent research progress on SCC of Mg alloys has been reviewed from the aspects of alloying,preparation process,surface modification,corrosive medium,and strain *** importantly,future research trends in the field of SCC of Mg alloys have also been proposed.

关键词： Magnesium alloys Stress corrosion cracking Alloying Preparation process Corrosion media Surface treatment