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International Journal of Minerals,Metallurgy and Materials 2022年第8期29卷 1570-1577页

作者： Lixin Hong Rongxiang Wang 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

In order to study the effects of Nd addition on microstructure and mechanical properties of Mg-Gd-Zn-Zr alloys,the microstruc-ture and mechanical properties of the as-cast Mg-12Gd-2Zn-xNd-0.4Zr(x=0,0.5wt%,and 1wt%)alloys were investigated by using optical microscope,scanning electron microscope,X-ray diffractometer,nano indentation tester,microhardness tester,and tensile testing machine.The results show that the microstructures mainly consist ofα-Mg matrix,eutectic phase,and stacking faults.The addition of Nd plays a significant role in grain refinement and uniform microstructure.The tensile yield strength and microhardness increase but the compression yield strength decreases with increasing Nd addition,leading to weakening tension-compression yield asymmetry in reverse of the Mg-12Gd-2Zn-xNd-0.4Zr alloys.The highest ultimate tensile strength(194 MPa)and ultimate compression strength(397 MPa)are obtained with 1wt%Nd addition of the alloy.

关键词： magnesium alloy neodymium microstructure stacking fault mechanical properties

Stress corrosion cracking of magnesium alloys:A review

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镁合金学报(英文) 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 performance.However,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 field.In 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 alloys.In this paper,the SCC mechanisms and test methods of Mg alloys have been summarized.The recent research progress on SCC of Mg alloys has been reviewed from the aspects of alloying,preparation process,surface modification,corrosive medium,and strain rate.More 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

Sequential ensemble optimization based on general surrogate model prediction variance and its application on engine acceleration schedule design

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Chinese Journal of Aeronautics 2021年第8期34卷 16-33页

作者： Yifan YE Zhanxue WANG Xiaobo zhang Shannxi Key Laboratory of Internal Aerodynamic in Aero-Engine School of Power and EnergyNorthwestern Polytechnical UniversityXi'an 710072China

The Efficient Global Optimization(EGO)algorithm has been widely used in the numerical design optimization of engineering systems.However,the need for an uncertainty estimator limits the selection of a surrogate model.In this paper,a Sequential Ensemble Optimization(SEO)algorithm based on the ensemble model is proposed.In the proposed algorithm,there is no limitation on the selection of an individual surrogate model.Specifically,the SEO is built based on the EGO by extending the EGO algorithm so that it can be used in combination with the ensemble model.Also,a new uncertainty estimator for any surrogate model named the General Uncertainty Estimator(GUE)is proposed.The performance of the proposed SEO algorithm is verified by the simulations using ten well-known mathematical functions with varying dimensions.The results show that the proposed SEO algorithm performs better than the traditional EGO algorithm in terms of both the final optimization results and the convergence rate.Further,the proposed algorithm is applied to the global optimization control for turbo-fan engine acceleration schedule design.

关键词： Cross-validation Efficient global optimization Engine acceleration schedule design Ensemble of surrogate models Gas turbine engine Optimization methods Surrogate-based optimization

Development of Geothermal Resources in China: A Review

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Journal of Earth Science 2018年第2期29卷 452-467页

作者： Xiaobo zhang Qinhong Hu School of Environmental Studies State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Department of Earth and Environmental Sciences University of Texas at Arlington

Geothermal resources in China are distributed throughout the country, with hydrother- real systems of high temperature in the Tibet Autonomous Region, Yunnan Province and Taiwan Island and hydrothermal systems of low-medium temperature mainly in various sedimentary basins. Devel- opment and exploration of geothermal energy in China are below expectations. The purpose of this study is to comparatively review the characteristics （geology, hydrogeology, hydrochemistry and geo- physical data） of typical hydrothermal fields/areas and suggest development and utilization approaches in the future. Hydrothermal systems formed by mountain Hfting contain a considerable amount of en- ergy for geothermal power generation, especially in the Tibet Autonomous Region, Yunnan Province and Taiwan Island. However, geothermal water in the Tatun geothermal field has high TDS （total dis- solved solids）, an issue that requires more research to resolve this problem for power generation. The large storage of geothermal resources has been investigated in Meso-Cenozoic sedimentary basins; it is basically used for heating, bathing or greenhouse plantation. Moreover, hydrothermal resources of low-medium temperature can also be used in binary power plants. Although the enhanced geothermal systems （EGS） in China are promising, the resources have not yet been commercially exploited, because the emerging technologies （hydraulic fracturing） and concerns over environmental impacts （induced miero-seismicity） lead to slow development. On the contrary, shallow geothermal energy has been di- rectly utilized mainly for heating and cooling buildings. Cities like Beijing, Tianjin and Shenyang have established a series of ground-source heat-pump systems, which has led to a massive reduction of CO2 emission of 19.87×10^6 t.

关键词： geothermal energy potential exploitation and utilization China.

Crustal Electrical Structure of the Wuwei Basin,Lower Yangtze Region of China,and Its Geological Implications

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Journal of Earth Science 2023年第6期34卷 1744-1757页

作者： Xiaobo zhang Penghui zhang Meixing He Dashuang He Fagen Pei Yaoyang zhang Yan Peng Institute of Geophysical and Geochemical Exploration Chinese Academy of Geological SciencesLangfang 065000China National Research Center for Geo-exploration Technology Langfang 065000China College of Earth Sciences Chengdu University of TechnologyChengdu 610059China

The Wuwei Basin is one of the most important oil-and gas-bearing basins in the Meso-Cenozoic basin groups in the Lower Yangtze River region.It has great shale gas resource prospects.The formation mechanism of this basin is poorly studied for lack of constraining data for deep structures.In this paper,a crustal electrical structure model of the Wuwei Basin and the adjacent areas is constructed based on the two-dimensional inversion of a magnetotelluric(MT)sounding profile achieved with the nonlinear conjugate gradient method.The results show that large-scale low-resistance bodies have developed in the underlying middle and lower crust of the Wuwei Basin,and are different from the uplifts on the two sides according to their high-resistance electrical characteristics.The electrical structure and regional geological and geophysical data suggest that the peak zone of the Chuzhou-Chaohu foreland fold-and-thrust belt is located on the east bank of the Yangtze River(Wuhu Section),which,together with the main thrust fault belt in the east,forms a typical thrust structure belt.An early Yanshanian sinistral strike-slip fault developed in the deep part of the Wuwei Basin,which may have controlled the formation and evolution of the basin,whereas the tectonic inversion of the early-developed thrust faults is relatively weak.These findings provide a geophysical basis for future studies of basin tectonic evolution and regional tectonic frameworks.

关键词： Wuwei Basin Lower Yangtze deep structure electrical structure fold-and-thrust belt shale gas magnetotellurics geophysics

Lightweight Deep Learning Models for High-Precision Rice Seedling Segmentation from UAV-Based Multispectral Images

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Plant Phenomics 2023年第4期5卷 876-892页

作者： Panli zhang xiaobo Sun Donghui zhang Yuechao Yang Zhenhua Wang College of Engineering Northeast Agricultural UniversityHarbin 150030China Aerospace Information Research Institute Chinese Academy of SciencesBeijing 100094China National Key Laboratory of Remote Sensing Information and Imagery Analyzing Technology Beijing Research Institute of Uranium GeologyBeijing 100029China College of Agriculture Northeast Agricultural UniversityHarbin 150030China

Accurate segmentation and detection of rice seedlings is essential for precision agriculture and high-yield cultivation.However,current methods suffer from high computational complexity and poor robustness to different rice varieties and densities.This article proposes 2 Iightweight neural network architectures,LW-Segnet and LW-Unet,for high-precision rice seedling segmentation.The networks adopt an encoder-decoderstructure with hybrid lightweight convolutions and spatial pyramid dilated convolutions,achieving accurate segmentation while reducing model parameters.Multispectral imagery acquired by unmanned aerial vehicle(UAV)was used to train and test the models covering 3 rice varieties and different planting densities.Experimental results demonstrate that the proposed LW-Segnet and LW-Unet models achieve higher F1-scores and intersection over union values for seedling detection and row segmentation across varieties,indicating improved segmentation accuracy.Furthermore,the models exhibit stable performance when handling different varieties and densities,showing strong robustness.In terms of efficiency,the networks have lower graphics processing unit memory usage,complexity,and parameters but faster inference speeds,reflecting higher computational efficiency.In particular,the fast speed of LW-Unet indicates potential for real-time applications.The study presents lightweight yet effective neural network architectures for agricultural tasks.By handling multiple rice varieties and densities with high accuracy,efficiency,and robustness,the models show promise for use in edge devices and UAVs to assist precision farming and crop management.The findings provide valuable insights into designing lightweight deep learning models to tackle complex agricultural problems.

关键词： seedling union weight

Simultaneously improving mechanical and anti-corrosion properties of extruded Mg-Al dilute alloy via trace Er addition

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Journal of Materials Science & Technology 2023年第19期150卷 49-64页

作者： Zhi zhang Jinshu Xie Jinghuai zhang Hao Dong Shujuan Liu Xiaobo zhang Jun Wang Ruizhi Wu Key Laboratory of Superlight Material and Surface Technology Ministry of EducationCollege of Materials Science and Chemical EngineeringHarbin Engineering UniversityHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology Nanjing Institute of TechnologyNanjing 211167China Ningbo Branch Ordnance Science Institute of ChinaNingbo 315103China

Simultaneously improving the mechanical properties and corrosion resistance of magnesium(Mg)alloys is a long-standing challenge to be solved in their engineering applications.In this work,we find that trace Er addition can improve the mechanical and anti-corrosion properties of Mg-1.4Al-0.4Mn-0.4Ca-0.3Er(wt%,AMXE)dilute alloy synergistically,especially reducing the corrosion rate(0.75 mm y-1)by one order of magnitude compared with the reference Mg-1.4Al-0.4Mn-0.4Ca(AMX)alloy and making it comparable to that of high-purity Mg.Adding trace Er reduces the dynamic recrystallization degree and increases the strengthening phase particles,which is mainly responsible for the increase of yield strength by 42 MPa.The addition of Er promotes the formation of much less noble Al8Mn4Er with effective Fe trapping ability and induces dislocation segregation,thus dramatically reducing micro-galvanic corrosion tendency.Meanwhile,Er addition promotes the formation of a more passivation and dense corrosion film.These two factors together lead to the extremely low corrosion rate of AMXE alloy.Our findings are expected to promote the development of low alloyed high performance Mg alloys.

关键词： Magnesium alloy Mechanics-corrosion synergy Rare earth element SKPFM

Recent developments on corrosion behaviors of Mg alloys with stacking fault or long period stacking ordered structures

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Journal of Magnesium and Alloys 2021年第4期9卷 1124-1148页

作者： Yujin Nie Jianwei Dai Xuan Li 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

Corrosion is one of the most drawbacks which restricts the wide applications of Mg alloys.In the last decade,the corrosion behaviors of Mg alloys with stacking fault(SF)and/or long period stacking ordered(LPSO)structures have obtained increasing attention.However,the corrosion mechanism of the SF–or LPSO–containing Mg alloys has not been well illustrated and even reverse results have been reported.In this paper,we have reviewed recent reports on corrosion behaviors of SF–or LPSO–containing Mg alloys to better clarify and understand the significance and mechanism.Moreover,some deficiencies are presented and advises are proposed for the development of corrosion resistant Mg alloys with SF or LPSO structures.

关键词： Magnesium alloys Corrosion behavior Stacking fault Long period stacking ordered

Distribution and assessment of hydrogeochemical processes of F-rich groundwater using PCA model:a case study in the Yuncheng Basin,China

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Acta Geochimica 2020年第2期39卷 216-225页

作者： Tao Liu Xubo Gao Xiaobo zhang Chengcheng Li School of Environmental Studies and State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074HubeiPeople's Republic of China Science and Technology Promotion Centre of Water Resources of Zhejiang Province HangzhouPeople's Republic of China

Hydrogeochemistry and factor analysis were conducted together to assess the distribution and the major geochemical processes in fluoride-contaminated shallow groundwater in the Yuncheng Basin.Spatially,fluoride concentration was low(<1.5 mg/L)in the southern piedmont plain,medium(<4 mg/L)in the central basin,and high(up to 14.1 mg/L)in Kaolao lowland areas in shallow aquifers.A three-factor principal component analysis model explained over 75.1%of the total variance.Sediment weathering leaching and evapotranspiration were recognized as the first primary hydrochemical processes response for the groundwater chemistry and explained the largest portion(42.1%)of the total variance.Factor two reflects the negative influence of human activities,with a positive loading of NO3^-and HCO3^-,and negative loading of well depth.Fluoride-bearing mineral dissolution and alkaline condition was ranked as the third factors responding for groundwater chemistry and explained 11.2%of the total variance.

关键词： Fluoride Groundwater chemistry PCA model Hydrogeochemical processes Yuncheng Basin

Characterization of DNA polymerase δ from deep-sea hydrothermal vent shrimp Rimicaris exoculata

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Acta Oceanologica Sinica 2021年第8期40卷 168-175页

作者： Wenlin Wu Hongyun Li Tiantian Ma Xiaobo zhang Fujian Province Key Laboratory for the Development of Bioactive Material from Marine Algae Quanzhou Normal UniversityQuanzhou 362000China College of Life Sciences Zhejiang UniversityHangzhou 310058China

DNA polymerase δ(Polδ)plays a crucial and versatile role in DNA replication and DNA repair processes.Vent shrimp Rimicaris exoculata is the primary megafaunal community living in hydrothermal vents.In this study,the Polδfrom shrimp Rimicaris exoculata was cloned,expressed and characterized.The results showed that the Polδcatalytic subunit(POLD1),852 amino acids in length,shared high homology with crayfish Procambarus clarkii and shrimp Oratosquilla oratoria.The recombinant POLD1 expressed in Escherichia coli showed that the enzyme was active in a range of 20℃ to 40℃ with an optimum temperature at 25℃ and in a wide range of p H with an optimum at pH 6.0.The activities of POLD1 were significantly enhanced in the presence of Triton-X 100,Tween 20 and Mn^(2+).The K_(m)(dNTP)value of POLD1 was 4.7μmol/L.The present study would be helpful to reveal the characterization of Polδof deep-sea vent animals.

关键词： deep-sea hydrothermal vent Rimicaris exoculata DNA polymeraseδ characterization