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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 er)er)erstanding the fracture properties of carbon allotropes and designing the carbon-based nanodevices.

关键词： Fracture toughness Graphyne Molecular dynamics Finite element

Progress in reentry trajectory planning for hypersonic vehicle

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Journal of Systems Engineering and Electronics 2014年第4期25卷 627-639页

作者： jiang zhao Rui Zhou Xuelian Jin School of Automation Science and Electrical Engineering Beihang University Beijing Microelectronics Technology Institute

The reentry trajectory planning for hypersonic vehicles is critical and challenging in the presence of numerous nonlinear equations of motion and path constraints, as well as guaranteed satisfaction of accuracy in meeting all the specified boundary conditions. In the last ten years, many researchers have investigated various strategies to generate a feasible or optimal constrained reentry trajectory for hypersonic vehicles. This paper briefly reviews the new research efforts to promote the capability of reentry trajectory planning. The progress of the onboard reentry trajectory planning, reentry trajectory optimization, and landing footprint is summarized. The main challenges of reentry trajectory planning for hypersonic vehicles are analyzed, focusing on the rapid reentry trajectory optimization, complex geographic constraints, and coop- erative strategies.

关键词： hypersonic vehicle reentry trajectory planning on-board planning reentry trajectory optimization footprint.

Electrolysis of ammonia for hydrogen production catalyzed by Pt and Pt-Ir deposited on nickel foam

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Journal of Energy Chemistry 2014年第1期23卷 1-8页

作者： Min jiang Dandan Zhu Xuebo zhao The Qingdao Key Lab of Solar Energy Utilization and Energy Storage Technology Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of Sciences

Electrolysis of ammonia in alkaline electrolyte solution was applied for the production of hydrogen. Both Pt-loaded Ni foam and Pt-Ir loaded Ni foam electrodes were prepared by electrodeposition and served as anode and cathode in ammonia electrolytic cell, respectively. The electrochemical behaviors of ammonia in KOH solution were individually investigated via cyclic voltammetry on three electrodes, i.e. bare Ni foam electrode, Pt-loaded Ni foam electrode and Pt-Ir loaded Ni foam electrode. The morphology and composition of the prepared Ni foam electrode were analyzed by scanning electron microscopy(SEM) and X-ray diffraction(XRD). Effects of the concentration of electrolyte solution and temperature of electrolytic cell on the electrolysis reaction were examined in order to enhance the efficiency of ammonia electrolysis. The competition of ammonia electrolysis and water electrolysis in the same alkaline solution was firstly proposed to explain the changes of cell voltage with the electrolysis proceeding. At varying current densities, different cell voltages could be obtained from galvanostatic *** low cell voltage of 0.58 V, which is less than the practical electrolysis voltage of water(1.6 V), can be obtained at a current density of2.5 mA/cm2. Based on some experimental parameters, such as the applied current, the resulting cell voltage and output of hydrogen gas, the power consumption per gram of H2produced can be estimated.

关键词： ammonia elelctrolysis nickel electrode hydrogen produciton catalyst power consumption

Component fault diagnosis for nonlinear systems

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Journal of Systems Engineering and Electronics 2016年第6期27卷 1283-1290页

作者： Junjie Huang Zhen jiang Junwei zhao School of Mechanical and Power Engineering Henan Polytechnic University School of Mechatronics Engineering and Automation Shanghai University

In the field of fault diagnosis, the state equation of nonlinear system, including the actuator and the component, has been established. When the faults in the system appear, it is difficult to observe the fault isolation between the actuator and the component. In order to diagnose the component fault in the nonlinear systems, a novel strategy is proposed. The nonlinear state equation with only the component system is built on mathematical equations. The nonlinearity of the component equation is expanded and estimated with Taylor series. If the actuator is perfect, the anomaly of the state equations reflects the component fault. The fault feature index is defined to detect the component fault and the initial fault. The numerical examples of the component faults are simulated for multiple-input multiple-output(MIMO)nonlinear systems. The results show that the component faults,as well as the incipient faults, can be detected. Furthermore, the effectiveness of the proposed strategy is verified. This method can also provide a foundation for the component fault reconfiguration control.

关键词： multiple-input multiple-output(MIMO) nonlinear systems component faults fault feature index fault diagnosis

Solidification Behavior of Immiscible Alloys under the Effect of a Direct Current

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Journal of Materials Science & Technology 2014年第10期30卷 1027-1035页

作者： Hongxiang jiang Jiuzhou zhao Jie He Institute of Metal Research Chinese Academy of Sciences

Directional solidification experiments were carried out with Al-Pb alloys under the effect of a direct current （DC）. The experimental results show that the DC causes a migration of the minority phase droplets （MPDs） from the middle part to the surface region of the sample, Samples with either a finely dispersed microstructure or a shell/ core structure were obtained by solidifying the alloy under the effect of the properly selected DC densities, A model was developed to describe the microstructure evolution in an immiscible alloy directionaliy solidified under the effect of the DC. The microstructure formation in the AI-Pb alloys was calculated. The numerical results are in favorable agreement with the experimental ones. They demonstrate that the DC affects the microstructure formation mainly through changing the spatial motions of the MPDs and the temperature field of the melt in front of the solid/liquid interface. The formation mechanisms of the finely dispersed microstructure as well as the shell/core structure were sufficiently clarified.

关键词： Rapid directional solidification Direct current Finely dispersed microstructure Shell/core structure

Influence of Strut Cross-section of Stents on Local Hemodynamics in Stented Arteries

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Chinese Journal of Mechanical Engineering 2016年第3期29卷 624-632页

作者： jiang Yongfei ZHANG Jun zhao Wanhua State Key Laboratory for Manufacturing System Engineering Xi'an Jiaotong University

Stenting is a very effective treatment for stenotic vascular diseases, but vascular geometries altered by stent implantation may lead to flow disturbances which play an important role in the initiation and progression of restenosis, especially in the near wall in stented arterial regions. So stent designs have become one of the indispensable factors needed to be considered for reducing the flow disturbances. In this paper, the structural designs of strut cross-section are considered as an aspect of stent designs to be studied in details. Six virtual stents with different strut cross-section are designed for deployments in the same ideal arterial model. Computational fluid dynamics（CFD） methods are performed to study how the shape and the aspect ratio（AR） of strut cross-section modified the local hemodynamics in the stented segments. The results indicate that stents with different strut cross-sections have different influence on the hemodynamics. Stents with streamlined cross-sectional struts for circular arc or elliptical arc can significantly enhance wall shear stress（WSS） in the stented segments, and reduce the flow disturbances around stent struts. The performances of stents with streamlined cross-sectional struts are better than that of stents with non-streamlined cross-sectional struts for rectangle. The results also show that stents with a larger AR cross-section are more conductive to improve the blood flow. The present study provides an understanding of the flow physics in the vicinity of stent struts and indicates that the shape and AR of strut cross-section ought to be considered as important factors to minimize flow disturbance in stent designs.

关键词： stent restenosis wall shear stress hemodynamics computational fluid dynamics

Three-dimensional cooperative guidance laws against stationary and maneuvering targets

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Chinese Journal of Aeronautics 2015年第4期28卷 1104-1120页

作者： zhao jiang Zhou Rui Dong Zhuoning School of Automation Science and Electrical Engineering Beihang University

This paper presents the cooperative strategies for salvo attack of multiple missiles based on the classical proportional navigation（PN） *** three-dimensional（3-D） guidance laws are developed in a quite simple formulation that consists of a PN component for target capture and a coordination component for simultaneous *** centralized algorithms come into effect when the global information of time-to-go estimation is obtained, whereas the decentralized algorithms have better performance when each missile can only collect information from *** simulations demonstrate that the proposed coordination algorithms are feasible to perform the cooperative engagement of multiple missiles against both stationary and maneuvering *** effectiveness of the 3-D guidance laws is also discussed.

关键词： Coordination algorithms Maneuvering target Missile guidance Multiple missiles Three-dimensional (3-D)

Preparation and Characterization of CA-MA Eutectic/Silicon Dioxide Nanoscale Composite Phase Change Material from Water Glass via Sol-Gel Method

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Journal of Wuhan University of Technology(Materials Science) 2017年第5期32卷 1048-1056页

作者：孟多 zhao Kang zhao Wei jiang Guowei School of Civil and Architectural Engineering Liaoning University of Technology Jinzhou 121001 China

This work mainly involved the preparation of a nano-scale form-stable phase change material（PCM） consisting of capric and myristic acid（CA-MA） binary eutectic acting as thermal absorbing material and nano silicon dioxide（nano-SiO_2） serving as the supporting material. Industrial water glass for preparation of the nano silicon dioxide matrix and CA-MA eutectic mixture were compounded by single-step sol-gel method with the silane coupling agent. The morphology, chemical characterization and form stability property of the composite PCM were investigated by transmission electron microscopy（TEM）, scanning electron microscopy（SEM）, Fourier-transform infrared（FT-IR） spectroscopy and polarizing microscopy（POM）. It was indicated that the average diameter of the composite PCM particle ranged from 30-100 nm. The CA-MA eutectic was immobilized in the network pores constructed by the Si-O bonds so that the composite PCM was allowed no liquid leakage above the melting temperature of the CA-MA eutectic. Differential scanning calorimetry（DSC） and thermogravimetric analysis（TGA） measurement were conducted to investigate the thermal properties and stability of the composite PCM. From the measurement results, the mass fraction of the CA-MA eutectic in the composite PCM was about 40%. The phase change temperature and latent heat of the composite were determined to be 21.15 ℃ and 55.67 J/g, respectively. Meanwhile, thermal conductivity of the composite was measured to be 0.208 W·m^（-1）·K^（-1） by using the transient hot-wire method. The composite PCM was able to maintain the surrounding temperature close to its phase change temperature and behaved well in thermalregulated performance which was verified by the heat storage-release experiment. This kind of form-stable PCM was supposed to complete thermal insulation even temperature regulation by the dual effect of relatively low thermal conductivity and phase change thermal storage-release properties. So it can be formulated that the nanos

关键词： fatty acid eutectic silicon dioxide nanoscale composite phase change material water glass sol-gel

Promoting and controlling electron transfer of furfural oxidation efficiently harvest electricity,furoic acid,hydrogen gas and hydrogen peroxide

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Journal of Energy Chemistry 2023年第4期79卷 135-147页

作者： Denghao Ouyang Daihong Gao Jinpeng Hong zhao jiang Xuebing zhao Key Laboratory of Industrial Biocatalysis Ministry of EducationTsinghua UniversityBeijing 100084China Institute of Applied Chemistry Department of Chemical EngineeringTsinghua UniversityBeijing 100084China School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049ShaanxiChina

Conventional chemical oxidation of aldehydes such as furfural to corresponding acids by molecular oxygen usually needs high pressure to increase the solubility of oxygen in aqueous phase,while electrochemical oxidation needs input of external electric ***,we developed a liquid flow fuel cell(LFFC)system to achieve oxidation of furfural in anode for furoic acid production with co-production of hydrogen *** controlling the electron transfer in cathode for reduction of oxygen,efficient generation of electricity or production of H_(2)O_(2)were *** oxides especially Ag_(2)O have been screened as the efficient catalyst to promote the oxidation of aldehydes,while liquid redox couples were used for promoting the kinetics of oxygen reduction.A novel alkaline-acidic asymmetric design was also used for anolyte and catholyte,respectively,to promote the efficiency of electron *** an LFFC system achieves efficient conversion of chemical energy of aldehyde oxidation to electric energy and makes full use the transferred electrons for high-value added products without input of external ***(VO_(2))_(2)SO_(4)as the electron carrier in catholyte for four-electron reduction of oxygen,the peak output power density(Pmax)at room temperature reached 261 mW/cm^(2)with furoic acid and H_(2)yields of 90%and 0.10 mol/mol furfural,*** anthraquinone-2-sulfonate(AQS)as the cathodic electron carrier,Pmaxof 60 mW/cm^(2)and furoic acid,H_(2)and H_(2)O_(2)yields of 0.88,0.15 and 0.41 mol/mol furfural were achieved,respectively.A new reaction mechanism on furfural oxidation on Ag_(2)O anode was proposed,referring to one-electron and two-electron reaction pathways depending on the fate of adsorbed hydrogen atom transferred from furfural aldehyde group.

关键词： Oxidation of furfural Liquid flow fuel cell Electricity generation Hydrogen production Electron transfer