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Effect of Heat Treatment on Microstructure and Mechanical Properties of Multiscale SiC_p Hybrid Reinforced 6061 Aluminum Matrix Composites

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 174-181页

作者：吴健铭许晓静 ZHANG xu LUO Yuntian LI Shuaidi HUANG Lin Institute for Advanced Manufacturing and Modern Equipment Technology Jiangsu UniversityZhenjiang 212013China

The performance of solid solution aging treatment on aluminum matrix composites prepared by powder metallurgy and reinforced with 6061 aluminum alloy powder as matrix;meanwhile, nano silicon carbide particles(nm Si Cp), submicron silicon carbide particles(1 μm Si Cp) and Ti particles were studied. The Al/Si Cp composite powder was prepared by high-energy ball milling, and then cold-pressed, sintered, hotextruded, and then heat-treated with different solution temperatures and aging times for the extruded composites. Optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy(EDS), X-ray diffractometer(XRD) and extrusion testing were used to analyze and test the microstructure and mechanical properties of aluminum matrix composites. The results show that after the multi-stage solid solution at 530 ℃×2 h+535 ℃×2 h+540 ℃×2 h, the particles are mainly equiaxed grains and uniformly distributed. There is no reinforcement agglomeration, and the surface is dense and the insoluble phase is basically dissolved. In the matrix, the strengthening effect is good, and the hardness and compressive strength are 179.43 HV and 680.42 MPa, respectively. Under this solution process, when the aluminum matrix composites are aged at 170 ℃ for 10 h, the hardness and compressive strength can reach their peaks and increase to 195.82 HV and 721.48 MPa, respectively.

关键词： aluminum matrix composites Si C particles multiscale hybrid enhancement heat treatment mechanical properties

Homological Epimorphisms, Compactly Generated t-Structures and Gorenstein-Projective Modules

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Chinese Annals of Mathematics,Series B 2018年第1期39卷 47-58页

作者： Nan GAO xiaojing xu Department of Mathematics Shanghai University Shanghai 200444 China

The aim of this paper is two-fold.Given a recollement(T′,T,T′′,i*,i_*,i~!,j!,j*,j*),where T′,T,T′′are triangulated categories with small coproducts and T is compactly generated.First,the authors show that the BBD-induction of compactly generated t-structures is compactly generated when i*preserves compact objects.As a consequence,given a ladder(T′,T,T′′,T,T′) of height 2,then the certain BBD-induction of compactly generated t-structures is compactly generated.The authors apply them to the recollements induced by homological ring epimorphisms.This is the first part of their work.Given a recollement(D(B-Mod),D(A-Mod),D(C-Mod),i*,i_*,i~!,j!,j*,j_*) induced by a homological ring epimorphism,the last aim of this work is to show that if A is Gorenstein,AB has finite projective dimension and j! restricts to D^b(C-mod),then this recollement induces an unbounded ladder(B-Gproj,A-Gproj,C-Gproj) of stable categories of finitely generated Gorenstein-projective modules.Some examples are described.

关键词： Compactly generated t-structure Recollement BBD-induction BPP-induction Homological ring epimorphism Gorensteinprojective module

The genome of the recretohalophyte Limonium bicolor provides insights into salt gland development and salinity adaptation during terrestrial evolution

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Molecular Plant 2022年第6期15卷 1024-1044页

作者： Fang Yuan Xi Wang Boqing Zhao xiaojing xu Miao Shi Bingying Leng Xinxiu Dong Chaoxia Lu Zhongtao Feng Jianrong Guo Guoliang Han Haikuan Zhang Jianwei Huang Min Chen Bao-Shan Wang Shandong Provincial Key Laboratory of Plant Stress College of Life SciencesShandong Normal UniversityJi’nanShandongChina Berry Genomics Corporation BeijingChina

Halophytes have evolved specialized strategies to cope with high salinity.The extreme halophyte sea lavender(Limonium bicolor)lacks trichomes but possesses salt glands on its epidermis that can excrete harmful ions,such as sodium,to avoid salt damage.Here,we report a high-quality,2.92-Gb,chromosome-scale L.bicolor genome assembly based on a combination of Illumina short reads,single-molecule,real-time long reads,chromosome conformation capture(Hi-C)data,and Bionano genome maps,greatly enriching the genomic information on recretohalophytes with multicellular salt glands.Although the L.bicolor genome contains genes that show similarity to trichome fate genes from Arabidopsis thaliana,it lacks homologs of the decision fate genes GLABRA3,ENHANCER OF GLABRA3,GLABRA2,TRANSPARENT TESTA GLABRA2,and SIAMESE,providing a molecular explanation for the absence of trichomes in this species.We identified key genes(LbHLH and LbTTG1)controlling salt gland development among classical trichome homologous genes and confirmed their roles by showing that their mutations markedly disrupted salt gland initiation,salt secretion,and salt tolerance,thus offering genetic support for the long-standing hypothesis that salt glands and trichomes may share a common origin.In addition,a whole-genome duplication event occurred in the L.bicolor genome after its divergence from Tartary buckwheat and may have contributed to its adaptation to high salinity.The L.bicolor genome resource and genetic evidence reported in this study provide profound insights into plant salt tolerance mechanisms that may facilitate the engineering of salt-tolerant crops.

关键词： development evolution genome Limonium bicolor salinity adaptation salt gland

Pers onal In come Tax Reform in China in 2018 and Its Impact on Income Distribution

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China & World Economy 2019年第3期27卷 25-48页

作者： Peng Zhan Shi Li xiaojing xu School of Economics Nanjing University of Finance & Economics China Institute for Income Distribution Beijing Normal University China

In the context of personal income tax(PIT)reform in China in 2018,this paper examines some of the major issues of concern regarding the reform and income distribution.Using the China Personal Income Tax Micro-simulation model,the paper compares the differences between the 2011 and 2018 PIT systems,and finds that residents relying on different income sources may face a large degree of real tax rate change.Once the tax system is altered to PIT 2018,the coverage of PIT for wage earners will decrease from 46.9 to 23.4 percent,the income redistributive effect will drop from 1.95 to 1.22 percent and the PITs role in fiscal revenue will also be negatively affected.Nevertheless,if individual income continues to grow,the share of PIT in fiscal revenue is expected to return to the 2018 level in 2022,but its income redistribution function is difficult to recover in the short term.The paper finds that the effect of PIT on income distribution depends on the tax structure.Gradual transition to an"entirely comprehensive"tax system when conditions are appropriate will achieve better income redistribution results at a lower average tax rate.

关键词： micro-simulation personal income tax reform residential income distribution

中国职业教育高质量发展水平测度、区域差异及空间效应

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职业技术教育 2024年第15期45卷 8-17页

作者：蔡文伯徐晓晶石河子大学师范学院石河子832003

我国已建立全球最大规模的职业教育体系,高质量发展是职业教育改革的关键议题。基于新发展理念,构建职业教育高质量发展评价指标体系,利用熵权法、Dagum基尼系数以及空间自相关分析测算2014-2022年中国职业教育高质量发展水平,并对全国... 详细信息

我国已建立全球最大规模的职业教育体系,高质量发展是职业教育改革的关键议题。基于新发展理念,构建职业教育高质量发展评价指标体系,利用熵权法、Dagum基尼系数以及空间自相关分析测算2014-2022年中国职业教育高质量发展水平,并对全国各区域各省份职业教育高质量发展的区域差异、空间效应进行分析。研究发现:中国职业教育高质量发展水平较低,总体发展水平呈波动上升趋势;区域间与区域内职业教育高质量发展水平均存在明显差异;空间上职业教育高质量发展水平呈现“高—高”集聚与“低—低”集聚特征。基于此,中国职业教育高质量发展的方向是:扬长补短,以新发展理念为指导,全面提高职业教育高质量发展水平;优化布局,以资源投入为牵引,缩小区域间职业教育高质量发展水平差距;因地制宜,以实际情况为基础,制定差异化职业教育高质量发展策略。

关键词：职业教育高质量发展测度体系区域差异空间效应

On the Distance Spectra of Several Double Neighbourhood Corona Graphs

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Journal of Mathematical Research with Applications 2019年第3期39卷 233-248页

作者： xiaojing xu Zhiping WANG Jiaxue xu Department of Mathematics Dalian Maritime University

Let G be a connected graph of order n and D（G） be its distance matrix. The distance eigenvalues of G are the eigenvalues of its distance matrix. Its distance eigenvalues and their multiplicities constitute the distance spectrum of G. In this article, we give a complete description of the eigenvalues and the corresponding eigenvectors of a block matrix D;. Further, we give a complete description of the eigenvalues and the corresponding eigenvectors of distance matrix of double neighbourhood corona graphs G;· {G;, G;}, G;· {G;, G;}, G;· {G;, G;},G;· {G;, G;}, where G is a complete graph and G;, G;are regular graphs.

关键词： corona distance spectrum double neighbourhood corona graph block matrix

Synchronization of switched Boolean networks with impulsive effects

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International Journal of Biomathematics 2018年第6期11卷 93-110页

作者： xiaojing xu Yansheng Liu Haitao Li Fuad E. Alsaadi School of Mathematics and Statistics Shandong Normal University Jinan 250014 P. R. China Department of Electrical and Computer Engineering Faculty of Engineering King Abdulaziz University Jeddah 21589 Saudi Arabia

This paper studies the state/output synchronization of switched Boolean networks (SBNs) with impulsive effects via the algebraic state space representation (ASSR) approach. First, an algebraic form is established for SBNs with impulsive effects via ASSR. Second, based on the algebraic form, some necessary and sufficient conditions are presented for the state/output synchronization of SBNs with impulsive effects under arbitrary switching signals. Third, two special kinds of switching signals, that is, free switching signal and feedback switching signal, are considered for the state synchronization of SBNs with impulsive effects. Finally, two illustrative examples are worked out to show the effectiveness of the obtained results.

关键词：布尔网络同步代数学信号形式经切换状态产量

Synthesis of monolithic carbon aerogels with high mechanical strength via ambient pressure drying without solvent exchange

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Journal of Materials Science & Technology 2020年第15期47卷 66-74页

作者： Zhi Yang Jian Li xiaojing xu Shengyang Pang Chenglong Hu Penglei Guo Sufang Tang Hui-Ming Cheng Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Aerospace Business Department China Academy of Launch Vehicle TechnologyBejing 100076China

A simple,fast and cost-effective method for monolithic carbon aerogels(CAs) preparation was proposed through sol-gel polycondensation of resorcinol with fo rmaldehyde in a basic aqueous solution followed by ambient pressure drying without solvent exchange,and carbonization.The microstructure and network strength of CAs were tailored by adju sting the catalyst concentration([resorcinol]/[sodium carbonate] in the range of 300-2000),water content([deionized water]/[resorcinol] equals to 17 and 24,respectively),and gelation temperature(Tgel in the range of 30-90℃).Resultantly,the CAs with a wide range of density(0.30-1.13 g/cm3),high specific surface area(465-616 m2/g),high compressive strength(6.5-147.4 MPa)and low thermal conductivity(0.065-0.120 W·m-1 K-1) were obtained in this work.Moreover,the largesized CAs(100×100×20 mm3) can also be prepared by this method since the formed robust skeleton network can resist shrinkage/collapse of pore structure and prevent cracking during drying.The improved mechanical strength and monolithic forming abilities could be mainly attributed to the uniform arrangement of carbon particles and pores,fine particle size,abundant network structure and enhanced particle neck.

关键词： Carbon aerogels Ambient pressure drying High mechanical strength Thermal insulation

The Normalized Laplacian Spectrum of Pentagonal Graphs and Its Applications

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Journal of Mathematical Research with Applications 2019年第4期39卷 343-352页

作者： xiaojing xu Peiwen WANG Zhiping WANG Faculty of Science Dalian Maritime University College of Shipping Economics and Management Dalian Maritime University

The eigenvalues of the normalized Laplacian of a graph provide information on its structural properties and also on some relevant dynamical aspects, in particular those related to random walks. In this paper, we give the spectra of the normalized Laplacian of iterated pentagonal of a simple connected graph. As an application, we also find the significant formulae for their multiplicative degree-Kirchhoffindex, Kemeny’s constant and number of spanning trees.

关键词： normalized Laplacian spectrum multiplicative degree-Kirchhoff index Kemeny’s constant the number of spanning trees