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A new method to determine the elastoplastic properties of ductile materials by conical indentation

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Science China(Physics,Mechanics & Astronomy) 2012年第6期55卷 1032-1036页

作者： ma ZengSheng ZHOU YiChun LONG ShiGuo LU ChunSheng Key Laboratory of Low Dimensional materials ＆ Application Technology of Ministry of Education Xiangtan University Xiangtan 411105 China Faculty of materials Optoelectronics and Physics Xiangtan University Xiangtan 411105 China Department of Mechanzcal Engineering Curtin University Perth WA 6845 Australia

Based on load-displacement curves,indentation is widely used to extract the elastoplastic properties of *** is generally believed that such a measure is non-unique and a full stress-strain curve cannot be obtained using plural sharp and deep spherical *** this paper we show that by introducing an additional dimensionless function of A/A (the ratio of residual area to the area of an indenter profile) in the reverse analysis,the elastoplastic properties of several unknown materials that exhibit visually indistinguishable load-displacement curves can be uniquely determined with a sharp indentation.

关键词： elastoplastic properties indentation reverse analysis

Review of Hydrogen Embrittlement in Metals: Hydrogen Diffusion, Hydrogen Characterization, Hydrogen Embrittlement Mechanism and Prevention

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Acta Metallurgica Sinica(English Letters) 2020年第6期33卷 759-773页

作者： Xinfeng Li Xianfeng ma Jin Zhang Eiji Akiyama Yanfei wang Xiaolong Song Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China State Key Laboratory for Mechanical Behavior of materials Xi'an Jiaotong UniversityXi'an 710049China Department of Physics and Astronomy Washington State UniversityPullmanWA 99164USA materials Design Division Institute for Materials ResearchTohoku UniversitySendai 980-8577Japan School of Chemical Engineering and Technology China University of Mining and TechnologyXuzhou 221116China

Hydrogen dissolved in metals as a result of internal and external hydrogen can affect the mechanical properties of the metals, principally through the interactions between hydrogen and material defects. Multiple phenomena such as hydrogen dissolution, hydrogen diffusion, hydrogen redistribution and hydrogen interactions with vacancies, dislocations, grain boundaries and other phase interfaces are involved in this process. Consequently, several hydrogen embrittlement(HE) mechanisms have been successively proposed to explain the HE phenomena, with the hydrogen-enhanced decohesion mechanism, hydrogenenhanced localized plasticity mechanism and hydrogen-enhanced strain-induced vacancies being some of the most important. Additionally, to reduce the risk of HE for engineering structural materials in service, surface treatments and microstructural optimization of the alloys have been suggested. In this review, we report on the progress of the studies on HE in metals, with a particular focus on steels. It focuses on four aspects:(1) hydrogen diffusion behavior;(2) hydrogen characterization methods;(3) HE mechanisms;and(4) the prevention of HE. The strengths and weaknesses of the current HE mechanisms and HE prevention methods are discussed, and specific research directions for further investigation of fundamental HE mechanisms and methods for preventing HE failure are identified.

关键词： Hydrogen embrittlement Hydrogen diffusion Hydrogen embrittlement mechanism prevention

盐胁迫对嫁接西瓜幼苗盐离子分布和生理特性的影响

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南方农业学报 2024年第6期55卷 1700-1712页

作者：李雪芳柳雪王西娜赵伟杰孙晶晶李小玉马纪龙何熙源马佳乐谭军利宁夏大学农学院宁夏银川750021 宁夏大学土木与水利工程学院宁夏银川750021

【目的】研究盐胁迫对嫁接西瓜幼苗盐离子分布和生理特性的影响,为调控盐胁迫下西瓜生长及合理开发利用地下微咸水和盐渍化土壤提供理论参考。【方法】以嫁接西瓜幼苗为试验材料,以营养液矿化度为2.5 g/L(对照,CK)的霍格兰营养液为基础... 详细信息

【目的】研究盐胁迫对嫁接西瓜幼苗盐离子分布和生理特性的影响,为调控盐胁迫下西瓜生长及合理开发利用地下微咸水和盐渍化土壤提供理论参考。【方法】以嫁接西瓜幼苗为试验材料,以营养液矿化度为2.5 g/L(对照,CK)的霍格兰营养液为基础,添加不同矿化度(3.0、3.5、4.0和4.5 g/L)微咸水溶液处理,测定不同处理下西瓜幼苗鲜重(FW)、干重(DW)、叶绿素相对含量(SPAD值)、不同组织中K^(+)、Na^(+)、Cl^(-)积累量和K^(+)/Na^(+)值及各项生理指标[超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和脯氨酸(Pro)、丙二醛(MDA)含量];并对各项指标进行相关性和主成分分析(PCA)以及盐胁迫阈值评价。【结果】随着微咸水矿化度的升高,西瓜幼苗植株的FW和DW均呈降低趋势,矿化度为4.0和4.5 g/L时,植株FW分别较CK显著降低33.38%和38.08%(P5.32 g/L。【结论】盐胁迫下,西瓜幼苗体内Na^(+)和Cl^(-)积累量降低植株对K^(+)吸收,破坏渗透调节物质和抗氧化酶系统,引起膜脂氧化,降低幼苗生物量;叶Pro含量、茎Cl^(-)积累量、叶和根MDA含量可作为西瓜幼苗遭受盐胁迫的综合评价指标。

关键词：盐胁迫西瓜盐分离子积累生理特性

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微气泡臭氧氧化+生化中试装置深度处理化工废水运行性能

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工业水处理 2024年第4期44卷 120-126页

作者：樊勤琦刘春穆思图张静郭延凯马俊俊河北科技大学环境科学与工程学院河北石家庄050018 河北省污染防治生物技术重点实验室河北石家庄050018

采用微气泡臭氧氧化+生化中试装置深度处理化工废水,对其长期连续运行性能进行评估并构建神经网络预测模型。结果表明,该中试装置能够稳定有效深度处理化工废水,微气泡臭氧氧化对COD和UV_(254)平均去除率分别为35.1%和52.5%,臭氧投加量... 详细信息

采用微气泡臭氧氧化+生化中试装置深度处理化工废水,对其长期连续运行性能进行评估并构建神经网络预测模型。结果表明,该中试装置能够稳定有效深度处理化工废水,微气泡臭氧氧化对COD和UV_(254)平均去除率分别为35.1%和52.5%,臭氧投加量与进水COD的质量比m是影响运行性能的重要参数,控制在0.5较为适宜。微气泡臭氧氧化处理可有效改善废水可生化性,BOD_(5)/COD由0.10提高至0.33,BOD_(5)增加量与COD去除量的比值可达到37.23%,对臭氧氧化后的废水进行生化处理,BOD_(5)去除量占COD去除量的80%以上。采用误差反向传播神经网络(BPNN)建立微气泡臭氧氧化处理中m对COD去除性能的预测模型,预测模型具有稳定的、较为精准的预测能力。

关键词：微气泡臭氧氧化生化中试装置深度处理化工废水预测模型

祁连山排露沟流域青海云杉天然更新空间关联性研究

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干旱区资源与环境 2024年第1期38卷 161-170页

作者：刘济萌刘贤德马瑞赵维俊敬文茂拓锋王艳霞甘肃农业大学林学院兰州730070 甘肃省祁连山水源涵养林研究院(甘肃祁连山森林生态系统国家定位观测研究站) 张掖734000 兰州大学草地农业科技学院兰州730000

青海云杉作为祁连山森林生态的建群种,其天然更新的空间关联性及集聚模式对种群更新具有重要意义。于2022年8月对祁连山排露沟流域海拔2800-3300m样地内的青海云杉林进行每木检尺,研究将胸径小于50mm的青海云杉植株划为更新苗,并选取更... 详细信息

青海云杉作为祁连山森林生态的建群种,其天然更新的空间关联性及集聚模式对种群更新具有重要意义。于2022年8月对祁连山排露沟流域海拔2800-3300m样地内的青海云杉林进行每木检尺,研究将胸径小于50mm的青海云杉植株划为更新苗,并选取更新苗胸径、株高两个生物指标,通过空间自相关分析探究其胸径、株高的空间关联性及集聚模式。结果表明:1)不同海拔更新苗胸径、株高均表现为空间正自相关,胸径空间关联性呈现为2800m>3100m>3000m>2900m>3300m,株高空间关联性呈现为2800m>2900m>3100m>3000m>3300m,仅3200m样地胸径和株高均表现为不显著的空间负自相关,表明更新苗胸径和株高的空间关联性随着海拔的升高而逐渐降低。2)不同样地更新苗胸径和株高个体间空间正自相关的数量远多于空间负自相关,表明青海云杉更新个体的生长有益于邻近径级个体的生长。3)更新苗胸径和株高整体呈现为低低集聚比高高集聚更为集中,且相互间分界明显,表明邻近径级的植株间关系较为协调,径级差异较大的植株间排斥效应较为明显。4)更新苗胸径和株高均表现出高高集聚和低低集聚交替分布的现象,且随着海拔的升高,高高集聚现象逐渐消失。

关键词：青海云杉天然更新空间自相关空间集聚

美洲大蠊肠道菌株wa5-1-7的初步鉴定及其抗菌活性成分的研究

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中国抗生素杂志 2024年第6期49卷 641-649页

作者：汪洁余田甜陈雪琴赵嘉怡刘文彬马艳金小宝广东药科大学基础医学院广东省生物活性药物研究重点实验室广州510006

目的对具有抗白念珠菌活性的美洲大蠊肠道来源菌株wa5-1-7进行形态学和分子生物学鉴定,并对其次级代谢物进行分离纯化,从中筛选具有抗菌活性的单体化合物。方法采用染色法和扫描电子显微镜观察菌株形态;利用PCR技术扩增菌株16S rRNA,通... 详细信息

目的对具有抗白念珠菌活性的美洲大蠊肠道来源菌株wa5-1-7进行形态学和分子生物学鉴定,并对其次级代谢物进行分离纯化,从中筛选具有抗菌活性的单体化合物。方法采用染色法和扫描电子显微镜观察菌株形态;利用PCR技术扩增菌株16S rRNA,通过其基因序列与NCBI数据库进行BLAST比对并采用N-J法构建系统发育树。菌株发酵后经乙酸乙酯溶剂萃取获得粗提物,粗提物经硅胶柱层析、葡聚糖凝胶柱层析、HPLC分离纯化,获得单体化合物,经核磁共振、质谱数据与文献比对鉴定化合物结构,并检测化合物的抗菌活性。结果菌株wa5-1-7初步鉴定为环圈链霉菌(Streptomyces anulatus),从粗提物中分离出10个化合物,分别为SF2738F(1)、SF2738D(2)、环(脯氨酸-亮氨酸)二肽(3)、SF2738A(collismycin A,4)、环(苯丙氨酸-脯氨酸)二肽(5)、SF2738C(6)、1H-吲哚甲醛(7)、大豆黄酮(8)、放线菌素X2(9)、放线菌素D(10),其中化合物4、9和10有较强抗菌活性。结论本研究从美洲大蠊肠道来源链霉菌次级代谢产物中分离出具有抗菌活性的单体化合物,为深入探索美洲大蠊肠道菌奠定了基础。

关键词：美洲大蠊链霉菌次级代谢产物抗菌活性

麻黄定喘汤辅助治疗对过敏性哮喘患儿气道炎症、重塑及Th1/Th2失衡的调节作用

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广州中医药大学学报 2024年第6期41卷 1479-1486页

作者：马永胜周峰然史曼曼临沂市中医医院山东临沂276000

【目的】探讨麻黄定喘汤辅助治疗对过敏性哮喘患儿气道炎症、重塑及辅助性T细胞1(Th1)/辅助性T细胞2(Th2)失衡的调节作用。【方法】将126例痰热壅肺型急性发作期过敏性哮喘患儿随机分为观察组与对照组,每组各63例。对照组给予常规西医治... 详细信息

【目的】探讨麻黄定喘汤辅助治疗对过敏性哮喘患儿气道炎症、重塑及辅助性T细胞1(Th1)/辅助性T细胞2(Th2)失衡的调节作用。【方法】将126例痰热壅肺型急性发作期过敏性哮喘患儿随机分为观察组与对照组,每组各63例。对照组给予常规西医治疗,观察组在对照组的基础上加用麻黄定喘汤治疗,总疗程为14 d。观察2组患儿治疗前后肺功能指标[第一秒用力呼气量(FEV1)和峰值呼气流速(PEF)]、气道炎症指标[痰液中的中性粒细胞、淋巴细胞、嗜酸性粒细数、单核细胞百分比和白细胞介素6(IL-6)、肿瘤坏死因子α(TNF-α)]、气道重塑指标[气道管壁面积(wa)、气道管腔面积(LA)、气道总面积(TA)]以及Th1/Th2细胞因子[干扰素γ(IFN-γ)、白细胞介素4(IL-4)]水平的变化情况,并评价2组患儿的临床疗效和安全性。【结果】(1)疗效方面,治疗14 d后,观察组的总有效率为93.65%(59/63),对照组为80.95%(51/63),组间比较(χ2检验),观察组的疗效明显优于对照组(Pwa值均较治疗前降低(Pwa值的降低幅度及LA、TA值升高幅度均明显优于对照组(P<0.05)。(5)Th1/Th2细胞因子方面,治疗后,2组患者的血清IFN-γ水平和IFN-γ/IL-4比值均较治疗前明显升高(P<0.05),血清IL-4水平均较治疗前明显降低(P<0.05),且观察组对血清IFN-γ水平和IFN-γ/IL-4比值的升高幅度及对血清IL-4水平的降低幅度均明显优于对照组(P<0.05)。(6)安全性方面,2组患儿治疗期间均未见严重不良反应,心电图、血常规、肝功能检查及心率、血压等安全性指标均未见明显异常。【结论】麻黄定喘汤有助于缓解过敏性哮喘患儿气道炎症、重塑,调节Th1/Th2失衡,改善患儿肺功能,疗效肯定,安全性好。

关键词：麻黄定喘汤痰热壅肺型过敏性哮喘气道炎症气道重塑 Th1/Th2失衡

Location optimization of multiple distribution centers under fuzzy environment

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第10期13卷 782-798页

作者： Yong waNG Xiao-lei ma Yin-hai waNG Hai-jun maO Yong ZHANG School of Transportation Southeast UniversiO Nanjing 210096 China Department of Civil and Environmental Engineering UniversiO of Washington Seattle WA 98195-2700 USA

Locating distribution centers optimally is a crucial and systematic task for *** located distribution centers can significantly improve the logistics system's efficiency and reduce its operational ***,it is not an easy task to optimize distribution center locations and previous studies focused primarily on location optimization of a single distribution *** growing logistics demands,multiple distribution centers become necessary to meet customers' requirements,but few studies have tackled the multiple distribution center locations(MDCLs) *** paper presents a comprehensive algorithm to address the MDCLs *** integration and clustering approach using the improved axiomatic fuzzy set(AFS) theory is developed for location clustering based on multiple hierarchical evaluation ***,technique for order preference by similarity to ideal solution(TOPSIS) is applied for evaluating and selecting the best candidate for each *** analysis is also conducted to assess the influence of each criterion in the location planning decision *** from a case study in Guiyang,China,reveals that the proposed approach developed in this study outperforms other similar algorithms for MDCLs *** new method may easily be extended to address location planning of other types of facilities,including hospitals,fire stations and schools.

关键词： Multiple distribution centers Location selection Clustering algorithm Axiomatic fuzzy set(AFS) Technique for order preference by similarity to ideal solution(TOPSIS)

Transit smart card data mining for passenger origin information extraction

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第10期13卷 750-760页

作者： Xiao-lei ma Yin-hai waNG Feng CHEN Jian-feng LIU Department of Civil and Environmental Engineering University of Washington Seattle WA 98195-2700 USA Beijing Transportation Research Center Beijing 100073 China

The automated fare collection(AFC) system,also known as the transit smart card(SC) system,has gained more and more popularity among transit agencies *** with the conventional manual fare collection system,an AFC system has its inherent advantages in low labor cost and high efficiency for fare collection and transaction data *** it is possible to collect highly valuable data from transit SC transactions,substantial efforts and methodologies are needed for extracting such data because most AFC systems are not initially designed for data *** is true especially for the Beijing AFC system,where a passenger's boarding stop(origin) on a flat-rate bus is not recorded on the check-in *** extract passengers' origin data from recorded SC transaction information,a markov chain based Bayesian decision tree algorithm is developed in this *** the time invariance property of the markov chain,the algorithm is further optimized and simplified to have a linear computational *** algorithm is verified with transit vehicles equipped with global positioning system(GPS) data *** verification results demonstrated that the proposed algorithm is effective in extracting transit passengers' origin information from SC transactions with a relatively high *** transit origin data are highly valuable for transit system planning and route optimization.

关键词： Transit smart card Automated fare collection(AFC) Bayesian decision tree markov chain Origin inference