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Stress corrosion cracking behavior of high-strength mooring-chain steel in the SO_(2)-polluted coastal atmosphere

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International Journal of Minerals,Metallurgy and Materials 2022年第6期29卷 1186-1196页

作者： menghao liu Zhiyong liu Cuiwei Du Xiaoqin Zhan Xiaojia Yang Xiaogang Li Corrosion and Protection Center University of Science and Technology BeijingBeijing 10083China Zhengmao Group Co. Ltd.Zhenjiang 212000China

21Cr2NiMo steel is widely used to stabilize offshore oil platforms;however,it suffers from stress-corrosion cracking(SCC).Herein,we studied the SCC behavior of 21Cr2NiMo steel in SO_(2)-polluted coastal *** tests revealed that the addition of SO_(2) increased the corrosion *** characterization showed that SO_(2) addition densified the corrosion products and promoted ***,slow strain rate tests demonstrated a high susceptibility to SCC in high SO_(2) *** morphologies revealed that the stress-corrosion cracks initiated at corrosion pits and the crack propagation showed transgranular and intergranular cracking *** conclusion,SCC is mix-controlled by anodic dissolution and hydrogen embrittlement mechanisms.

关键词： corrosion marine atmospheres mooring-chain steel SO_(2)-polluted coastal atmospheres stress-corrosion cracking

Effect of cathodic potential on stress corrosion cracking behavior of 21Cr2NiMo steel in simulated seawater

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International Journal of Minerals,Metallurgy and Materials 2022年第2期29卷 263-270页

作者： menghao liu Zhiyong liu Cuiwei Du Xiaoqin Zhan Chunduo Dai Yue Pan Xiaogang Li Corrosion and Protection Center University of Science and Technology BeijingBeijing 10083China Zhengmao Group Co. Ltd.Zhenjiang 212000China

This study aims at providing systematically insights to clarify the impact of cathodic polarization on the stress corrosion cracking(SCC)behavior of 21 Cr2 NiMo ***-strain-rate tensile tests demonstrated that 21 Cr2 NiMo steel is highly sensitive to hydrogen embrittlement at strong cathodic *** lowest SCC susceptibility occurred at-775 mV ***,whereas the SCC susceptibility was remarkably higher at potentials below-950 mV *** electron microscopy(SEM)and electron backscattered diffraction(EBSD)revealed that the cathodic potential decline caused a transition from transgranular to intergranular mode in the fracture *** intergranular mode transformed from bainite boundaries separation to prior austenitic grain boundaries separation under stronger cathodic ***,corrosion pits promoted the nucleation of SCC *** conclusion,with the decrease in the applied potential,the SCC mechanism transformed from the combination of hydrogen embrittlement and anodic dissolution to typical hydrogen embrittlement.

关键词： stress corrosion cracking cathodic potential hydrogen embrittlement seawater high-strength low-alloy steel

Multi-Patch Black-White Topology Optimization in Isogeometric Analysis

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Computer Modeling in Engineering & Sciences 2023年第1期134卷 459-481页

作者： Qingyuan Hu Yuan Liang menghao liu Manfeng Hu Yawen Mao School of Science Jiangnan UniversityWuxi214122China Department of Engineering Mechanics Dalian University of TechnologyDalian116024China

Topological optimization plays a guiding role in the conceptual design *** paper conducts research on structural topology optimization algorithm within the framework of isogeometric *** multi-component structures,the Nitsche’smethod is used to glue differentmeshes to performisogeometricmulti-patch *** discrete variable topology optimization algorithm based on integer programming is adopted in order to obtain clear boundaries for topology *** sensitivity filtering method based on the Helmholtz equation is employed for averaging of curved elements’*** addition,a simple averaging method along coupling interfaces is proposed in order to ensure the material distribution across coupling areas is reasonably ***,the performance of the algorithm is demonstrated by numerical examples,and the effectiveness of the algorithm is verified by comparing it with the results obtained by single-patch and ABAQUS cases.

关键词： Isogeometric topology optimization nitsche multi-patch integer programming

Multi-Objective Optimization of the Spatial Structure and Layout of the Protected Area Based on Ecosystem Services: A Case Study of the Yellow River's Headwaters Region in the Three-River-Source National Park

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Chinese Journal of Urban and Environmental Studies 2021年第3期9卷 57-77页

作者： liu menghao XI Jianchao Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences University of Chinese Academy of Sciences

The optimization of the spatial structure and layout is to determine an optimal and cost-effective land-use allocation plan for protected areas. The key goal is to maximizing the value of ecosystem services. This paper establishes a framework for optimizing the spatial structure and layout of the protected area based on ecosystem services. With the objective of maximizing the value of ecosystem services, it uses the CoMOLA(Constrained Multi-objective Optimization of Land-use Allocation) model for multi-objective optimization under the constraints of area and conversion rules. Taking the Yellow River’s headwaters region in the Three-River-Source(Sanjiangyuan) National Park as the study area, this paper uses the data of the year 2015 as a benchmark, and obtains the optimization results of the study area by 2035. The results show that the total value of ecosystem services of the Yellow River’s headwaters region after optimization will reach RMB 5.61 × 1010,with a total increase of RMB 43.84 × 10~8(8.47%). The land covers that contribute most to the value of ecosystem services are rivers, lakes and wetlands(51.55%), and grasslands(40.71%). Among the various types of ecosystem services, the value of provisioning services will increase by RMB 2.32 × 10~8, regulating services by RMB 35.23 × 10~8, supporting services by RMB 0.58 × 10~8,and cultural services by RMB 5.70 × 10~8. The research results can provide a scientific basis for the spatial optimization of protected areas and the management of national parks.

关键词： Protected area ecosystem services spatial optimization the Three-River-Source National Park

Bacillus tropicus来源β-D-呋喃果糖苷酶基因的克隆与表达及其酶学特性研究

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河南工业大学学报（自然科学版） 2024年第2期45卷 1-10页

作者：王润任彤宋衍银沈艺梅李雨禅刘梦昊李思霆陈洲北京工商大学食品与健康学院北京100048

为获得新β-D-呋喃果糖苷酶资源并探究其酶学性质及在转化糖中的应用潜力,挖掘出Bacillus tropicus来源的β-D-呋喃果糖苷酶基因BtFFase8,成功合成后表达在大肠杆菌宿主中。通过数据库筛选β-D-呋喃果糖苷酶的基因序列,将基因克隆至载体... 详细信息

为获得新β-D-呋喃果糖苷酶资源并探究其酶学性质及在转化糖中的应用潜力,挖掘出Bacillus tropicus来源的β-D-呋喃果糖苷酶基因BtFFase8,成功合成后表达在大肠杆菌宿主中。通过数据库筛选β-D-呋喃果糖苷酶的基因序列,将基因克隆至载体pET-28a(+)中。将获得的重组质粒转化至大肠杆菌BL21,构建重组菌株大肠杆菌BL21/pET28a-BtFFase8。采用亲和层析纯化克隆酶,用SDS-PAGE法分析蛋白分子量,通过葡萄糖试剂盒检测酶水解产物的能力得到酶活力,用福林酚试剂法测定蛋白质含量。克隆酶BtFFase8的分子质量为57.0 kDa,对蔗糖底物的比酶活力为13.4 U/mg;BtFFase8的最适pH和最适温度分别为pH 6.5和45℃,且在pH 5.0~8.0和40℃及以下温度保持酶活力稳定,残余酶活力大于80%;BtFFase8能耐受碱性蛋白酶、酸性蛋白酶和胰蛋白酶的水解,残余酶活力大于70%。BtFFase8的发现及克隆酶优良的酶学功能为其未来应用于食品加工,特别是在转化糖的生产中奠定了良好的理论基础。

关键词： β-D-呋喃果糖苷酶 Bacillus tropicus 异源表达酶学性质转化糖

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一种配备双工位快速换模台架的液压机

锻压装备与制造技术 2024年第4期59卷 26-31页

作者：刘盼中崔鹏梁伟立段君艳刘梦豪天津市天锻压力机有限公司天津300142

扣合包边液压机是实现汽车门盖压合包边工艺的关键装备。本文介绍扣合包边液压机及其快速换模装置的基本组成要素,对关键技术进行试验研究,对其应用优势进行了总结展望。

关键词：扣合包边液压机快速换模装置关键技术双工位

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Study on the Spatial Coupling between Expressway Networks and Tourist Attractions: A Case Study of Guizhou Province

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Chinese Journal of Urban and Environmental Studies 2020年第1期8卷 17-36页

作者： CHEN Sihong XI Jianchao liu menghao Key Laboratory of Regional Sustainable Development Modeling Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences College of Resource and Environment University of Chinese Academy of Sciences

Transportation is the most basic element in the development of tourism, with expressways being the main channel for tourism transportation in the era of driving tours. The relationship between transportation and tourism development has always been one of the hot topics in tourism geography study. Since the expressway service area is the main node of tourist service facilities in the expressway transportation network, we conducted a field research on 125 service areas and 177 tourist attractions in Guizhou Province, and obtained relevant data. By using the centrality measures for social network analysis, and combining the kernel density analysis with bivariate spatial autocorrelation analysis, this paper explores the centrality characteristics of expressway transportation network, the spatial distribution regularity of tourist attractions, and the spatial coupling between them. The main study conclusions are as follows:(1) The expressway service areas in Guizhou Province gradually decrease from a single core to the periphery.(2) The spatial distribution of tourist attractions presents a weak circular structure with multiple cores in a scattered manner, and the regional differences are apparent.(3) There is positive spatial correlation between the expressway networks and tourist attractions. The spatial coupling between the expressway transportation network and tourist attractions can be divided into four types of clusters:high–high cluster, high–low cluster, low–high cluster, and low–low cluster, with high–high and low–low clusters as the main types. The high–high cluster is the area with the best coupling effect and the most mature tourism. The high–low and low–high clusters have a mismatch between transportation and tourism resources. For such clusters, the spatial coupling can be realized by changing the functions of the service area or improving the quality of the tourist attraction. They have great development potential. The low–low cluster is far away from tour

关键词： Expressway tourist attraction network centrality spatial coupling transportation and tourism integration

The risk factors and threshold level of subchronic inhalation exposure of reclaimed water

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Journal of Environmental Sciences 2024年第3期137卷 639-650页

作者： Jiayang Kong Yun Lu Yunru Ren menghao Chen Gang liu Liangliang Shi State Key Joint Laboratory of Environment Simulation and Pollution Control State Environment Protection Key Laboratory of Microorganism Application and Risk ControlSchool of EnvironmentTsinghua UniversityBeijing 100084China

Inhalation of reclaimed water is known to cause lung infammation,and free endotoxins have been shown to be a major risk factor for acute *** exposure has also been shown to induce infammatory responses with visible tissue ***,subchronic risk factors have yet to be identified,and a threshold for the protection of occupational populations during urban reuse is *** this study,potential risk factors in reclaimed water were examined by subchronic exposure with fractionated reclaimed water,and the health risk threshold was tested with a series of diluted reclaimed ***,following a 12-week exposure,macromolecules and microorganisms were found to be two major risk factors in reclaimed water that could cause pulmonary infammation,including increased proportion of polymorphonuclear leukocytes in bronchoalveolar fuid,formation of inducible bronchus-associated lymphoid tissue,and elevation of Immunoglobulin A ***,infammation persisted after a 4-week recovery *** calculated threshold of reclaimed water exposure for mice was 31.8 Endotoxin Unit(EU)/(kg·day)under when exposed to 50%additional relative humidity from reclaimed water at 25℃ for 2 hr/***,the subchronic threshold estimate for humans under the same exposure conditions was found to be 12.2 EU/(kg·day),corresponding to endotoxin levels of 61.7 EU/mL in reclaimed *** threshold level of endotoxin was lower than that in most non-potable reclaimed *** findings of this study suggest that occupational exposure of reclaimed water can serve as a potential risk to workers.

关键词： Reclaimed water Inhalation exposure Risk factor Threshold Infammation Endotoxin

Inversion method of deflection of the vertical based on SWOT wide-swath altimeter data

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Geodesy and Geodynamics 2024年第4期15卷 419-428页

作者： Xin liu menghao Song Chao Li Guihua Hui Jinyun Guo Yongjun Jia Heping Sun College of Geodesy and Geomatics Shandong University of Science and TechnologyQingdao 266590China Weicheng Branch of Natural Resources and Planning Bureau of Weifang City Weifang 261021China National Satellite Ocean Application Service Beijing 100081China State Key Laboratoryof Geodesy and Earth's Dynamics Innovation AcademyforPrecision Measurement Science and TechnologyChinese Academy of ScienceWuhan 420071China

The deflection of the vertical(DOV)is the key information in the study of ocean gravity ***,in most areas,the precision of the prime component of DoV is significantly lower than that of the meridian *** obtain higher accuracy and resolution of ocean gravity information,researchers have proposed a novel altimeter called the wide-swath *** altimeter allows for the simultaneous acquisition of high-precision and high-resolution two-dimensional measurements of sea surface height(SSH).In this paper,the Surface Water and Ocean Topography(SWOT)mission with a wide-swath altimeter on board is selected for *** cycle of swoT sea surface height data is simulated to inverse the DOV in the Arabian Sea(45°E—80°E,0°-30°N),and the inversion results are compared with those of conventional altimeter *** results demonstrate that the difference between the meridian and prime components derived from the inversion of swoT wide-swath data is minimal,significantly outperforming the inversion results of conventional nadir altimeter *** advantage of swoT wide-swath altimeter lies in its ability to use the multi-directional geoid slope at any sea surface measurement point to invert the components in the meridian and prime *** investigate the impact of this advantage on inversion precision,this paper employs a method to calculate the gradient of the geoid in multiple directions to invert DoV *** improvement effect of calculating the gradient of the geoid in multiple directions on the precision of DoV component is *** is found that the accuracy of DoV inversion has significantly improved with the increase of geodetic gradient calculation *** addition,the effects of various errors and grid spacing in SwoT wide sea surface height data on the precision of Dov inversion are also analyzed.

关键词： SWOT Wide-swath altimeter Inversion method of Dov Multi-directional Arabian sea