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A comparative analysis of reticular crack on ceramic plate driven by thermal shock

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Science China(Physics,Mechanics & Astronomy) 2016年第7期59卷 46-51页

作者： XiangHong xu ShiLong Sheng Cheng Tian WenJun Yuan State Key Laboratory of Nonlinear Mechanics(LNM) Institute of Mechanics Chinese Academy of Sciences

Reticular crack is generally found on the surface of ceramic material that has been subjected to a thermal-shock condition. In the present study, a quantitative effect of thermal shock and quench temperature has been studied and investigated. Experimental tests were carried out to characterize the reticular crack that has been found in the Ge Kiln, which is a famous art of the ancient Chinese culture. After comparative analysis between thermal-shock cracks and the glaze crack patterns of the Ge Kiln porcelain,it is found that this study is expected to provide a powerful tool for recurrence of the long-lost firing and cooling process of the Ge Kiln porcelain.

关键词： reticular crack thermal shock ceramics Ge Kiln porcelain

A MESH-FREE ALGORITHM FOR DYNAMIC IMPACT ANALYSIS OF HYPERELASTICITY

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Acta Mechanica Solida Sinica 2013年第4期26卷 362-372页

作者： De’an Hu Zhanhua Sun Chao Liang xu Han State Key Laboratory of Advanced Design and Manufacture for Vehicle Body Hunan University

A mesh-free method based on local Petrov-Galerkin formulation is presented to solve dynamic impact problems of hyperelastic *** the present method,a simple Heaviside test function is chosen for simplifying domain *** function is constructed by using a radial basis function （RBF） coupled with a polynomial basis function,in which the shape function possesses the kronecker delta function ***,additional treatment is not required for imposing essential boundary *** equations of impact problems are established and solved node by node by using an explicit time integration algorithm in a local domain,which is very similar to that of the collocation method except that numerical integration can be implemented over local domain in the present *** results for several examples show that the present method performs well in dealing with the dynamic impact problem of hyperelastic material.

关键词： mesh-free method dynamic impact problem hyperelasticity explicit algorithm

Distributed quantized mirror descent for strongly convex optimization over time-varying directed graph

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Science China(Information Sciences) 2022年第10期65卷 196-210页

作者： Menghui XIONG Baoyong ZHANG Deming YUAN Shengyuan xu School of Automation Nanjing University of Science and Technology

This paper investigates a distributed strongly convex constrained optimization problem in the non-Euclidean sense, where the bit rate of the considered communication between nodes is assumed to be limited, and the communication topology is represented by a time-varying directed graph. By considering the limitation of communication capacity, the quantization technique is applied in the process of exchanging information over the network. Then a distributed quantized mirror descent(DQMD) algorithm, which uses the Bregman divergence and time-varying quantizers, is developed for the strongly convex optimization under a convex constraint set. The convergence of the developed algorithm is also analyzed. It is shown that the nodes' state errors are bounded by some terms related to the quantization resolutions, and the sublinear upper-bounds can be guaranteed by choosing appropriate quantization resolutions. Finally, a distributed ridge regression is provided as an example to verify the validity of the proposed method.

关键词： distributed convex optimization strongly convex optimization mirror descent quantized communication Bregman divergence

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Seismic experimental study on a concrete pylon from a typical medium span cable-stayed bridge

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Frontiers of Structural and Civil Engineering 2018年第3期12卷 401-411页

作者： Yan xu Shijie ZENG Xinzhi DUAN Dongbing JI State Key Laboratory for Disaster Reduction in Civil Engineering Tongji University Shanghai 200092 China i University Shanghai 200092 China Shanghai Municipal Planning and Design Research Institute Shanghai 200031 China Jiangsu Province Communications Planning and Design Institute Limited Company Nanjing 210014 China

According to the current seismic design codes of bridges in China, cable-stayed bridges have been usually required to remain elastic even subjected to strong earthquakes. However, the possibilities of pylon plastic behavior were revealed in recent earthquake damages. The lack of due diligence in the nonlinear seismic behavior of the pylon has caused a blurry understanding about the seismic performance of such widely built though less strong earthquake experienced structures. In light of this point, a 1/20 scaled concrete pylon model which from a typical medium span cable-stayed bridge was designed and tested on the shaking table longitudinally. The dynamic response and seismic behavior of the pylon were measured, evaluated and compared to reveal its vulnerable parts and nonlinear seismic performance. The results show that most parts of the concrete pylon remain elastic even under very strong excitations, which means a sufficient safety margin for current pylon longitudinal design. The most vulnerable parts of the pylon appeared first at the pylon bottom region, cracks opening and closing at the pylon bottom were observed during the test, and then extended to the lower column and middle column around the lower strut.

关键词： cable-stayed bridge pylon shaking table test seismic behavior

NHPP-based software reliability model considering testing effort and multivariate fault detection rate

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Journal of Systems Engineering and Electronics 2016年第1期27卷 260-270页

作者： Jie Zhang Yang Lu Shu Yang Chong xu School of Computer and Information Hefei University of Technology Hefei 230009 China School of Mathematics and Computer Science Anhui Normal University Wuhu 241003 China

In recent decades,many software reliability growth models（SRGMs） have been proposed for the engineers and testers in measuring the software reliability *** of them is established based on the non-homogeneous Poisson process（NHPP）,and it is proved that the prediction accuracy of such models could be improved by adding the describing of characterization of testing ***,some research work indicates that the fault detection rate（FDR） is another key factor affects final software *** early NHPPbased models deal with the FDR as constant or piecewise function,which does not fit the different testing stages ***,this paper first incorporates a multivariate function of FDR,which is bathtub-shaped,into the NHPP-based SRGMs considering testing effort in order to further improve performance.A new model framework is proposed,and a stepwise method is used to apply the framework with real data sets to find the optimal *** studies show that the obtained new model can provide better performance of fitting and prediction compared with other traditional SRGMs.

关键词： software reliability software reliability growth mo del(SRGM) testing effort fault detection rate(FDR).

Different compositions of TC4/TC11 functional gradient materials interface by wire arc additive manufacturing

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Science China Technological Sciences 2024年第12期67卷 3777-3782页

作者： WANG JiaChen WANG He xu TianQiu LIU ChangMeng School of Infrastructure Engineering Nanchang University Beijng Aerospace FeiTeng Equipment Technology Co. Ltd. Department of Mechanical Engineering Politecnico di Milano School of Mechanical Engineering Beijing Institute of Technology

Titanium alloy is widely utilized in diverse industries due to its exceptional specific strength, making it a material with significant potential for advancement. Nevertheless, homogeneous materials are inadequate to meet the demands of various *** gradient materials(FGMs) have garnered increasing interest for their ability to tailor materials and structures. The continuous transition in FGMs often offers a more uniform and well-connected interface. However, there remains a lack of comprehensive research on the transition interface. In this study, TC4/TC11 double-alloy materials were produced using doublewire additive manufacturing. The wire feeding rates were adjusted to create materials with varying compositions. The grain morphologies, microstructures, and mechanical properties were examined. It was observed that as the TC11 content increased,the grain size decreased, the β content rose, the ultimate tensile strength improved, and the elongation decreased. Additionally,analysis of the fracture morphologies revealed that the dimples became smaller, indicating characteristics of ductile *** the solid solution aging heat treatment, it is observed that the α phase increases in size, and the mechanical properties are enhanced. These observations indicate that double-wire additive manufacturing can produce diverse interfaces. Furthermore,the heat treatment process has been shown to enhance the material properties, thus establishing an experimental foundation for FGMs.

关键词： additive manufacturing functional gradient materials titanium alloys transitional layers

Two-dimensional porous carbon derived from pollen with enlarged interlayer distance enhanced electrocatalytic oxidation of n-valeraldehyde to octane

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Nano Research 2024年第5期17卷 3455-3461页

作者： Meichun Qin Chaolong Liu Shouhen xu Jianguo Tang Institute of Hybrid Materials National Center of International Joint Research for Hybrid Materials TechnologyNational Base of International Sci.and Tech.Cooperation on Hybrid MaterialsCollege of Materials Science and EngineeringQingdao UniversityQingdao266071China Department of Pharmaceutics School of PharmacyQingdao UniversityQingdao266071China

Electrocatalytic n-valeraldehyde oxidation reaction was an inexpensive and eco-friendly method to control n-valeraldehyde contamination and produce high value-added ***,low-cost and readily available electrocatalysts with high current efficiency were urgently ***,two-dimensional porous carbon derived from pollen with enlarged interlayer distance was built by alkali activation method,applying in electrocatalytic n-valeraldehyde oxidation *** enlarged interlayer distance was verified by X-ray diffraction(XRD)and high-angle annular dark-field scanning transmission electron microscope(HAADF-STEM).Electrocatalytic experiments consequences showed activated biomass derived carbon possessed a higher electrocatalytic activity and octane selectivity than unactivated *** tests and in situ infrared experiments demonstrated that enlarged interlayer distance was positively correlated with specific surface area of catalysts,large specific surface area provided abundant absorption sites,facilitated the adsorption for n-valeraldehyde,and further promoted the transformation of n-valeraldehyde to *** work also provides a new avenue for creating high-performance electrocatalysts in terms of lattice engineering.

关键词： biomass derived carbon lattice expansion high specific surface area upgrade of n-valeraldehyde

Effect of nitrogen/phosphorus concentration on algal organic matter generation of the diatom Nitzschia palea:Total indicators and spectroscopic characterization

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Journal of Environmental Sciences 2016年第9期28卷 130-142页

作者： Linlin Han Bingbing xu Fei Qi Zhonglin Chen Beijing Key Laboratory for Source Control Technology of Water Pollution College of Environmental Science and EngineeringBeijing Forestry University State Key Laboratory of the Environmental Criteria and Risk Assessment Chinese Research Academy of Environmental Sciences State Key Laboratory of Urban Water Resource and Environment Harbin Institute of Technology

Critical algal blooms in great lakes increase the level of algal organic matters（AOMs）,significantly altering the composition of natural organic matters（NOMs） in freshwater of *** study examined the AOM＇s characteristics of Nitzschia palea（***）,one kind of the predominant diatom and an important biomarker of water quality in the great lakes of China,to investigate the effect of AOMs on the variation of NOMs in lakes and the process of algal ***–emission matrix fluorescence（EEM） spectroscopy,synchronous fluorescence（SF） spectroscopy and deconvolution UV–vis（D-UV） spectroscopy were utilized to characterize AOMs to study the effects of nutrient loading on the composition change of *** results,it was revealed that the phosphorus is the limiting factor for ***＇s growth and the generation of both total organic carbon and amino acids but the nitrogen is more important for the generation of carbohydrates and *** spectra revealed differences in the composition of extracellular organic matter and intracellular organic *** of the nitrogen and phosphorus concentrations,aromatic proteins and soluble microbial products were the main components,but the nitrogen concentration had a significant impact on their *** SF spectra were used to study the AOMs for the first time and identified that the protein-like substances were the major component of AOMs,creating as a result of aromatic group *** D-UV spectra showed carboxylic acid and esters were the main functional groups in the EOMs,with –OCH_3,–SO_2NH_2,–CN,–NH_2,–O– and –COCH_3functional groups substituting into benzene rings.

关键词： Extracellular organic matter Intracellular organic matter Nitzschia palea Fluorescence spectroscopy Deconvolution UV–vis spectroscopy

Effect of Aspect Ratio on the Evolution of Shear Bands in Zr_(61.7)Al_8Ni_(13)Cu_(17)Sn_(0.3)Bulk Metallic Glass

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Journal of Materials Science & Technology 2017年第1期33卷 99-104页

作者： Wenli Ma Yuanli xu Bo Shi Jiangong Li Institute of Materials Science and Engineering and MOE Key Laboratory for Magnetism and Magnetic Materials Lanzhou UniversityLanzhou 730000China

Zr61.7A18Ni13Cu17Sn0.3 bulk metallic glass samples with different aspect ratios in the range of 0.25-2.25 were deformed by compression, and the effect of aspect ratio on the evolution of shear bands was investigated. It is found that for the deformed Zr61.7AlaNi13CulTSno3 bulk metallic glass, the average shear band spacing decreases and the shear band density increases monotonically as the aspect ratio increases from 0.25 to 2.25. A minimal average shear band spacing of 0.478μm is achieved for the sample with an aspect ratio of 2.25. In addition, the fractions of shear bands with spacings below 100 and 50 nm are about 12.84% and 6.76%, respectively, for the sample with an aspect ratio of 2.25. The reason for the formation of a higher density of shear bands can probably be attributed to the increase of the driving force for the samole with a larger aspect ratio.

关键词： Metallic glass Aspect ratio Shear band Compressive deformation