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Effect of nanoparticles on the nucleation and agglomeration rates of hydrate growth using THF-water clathrates

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Petroleum Science 2020年第2期17卷 467-476页

作者： Syed Y.Nahri James L.Nielsen yuanhang Chen Craft and Hawkins Department of Petroleum Engineering Louisiana State UniversityBaton RougeLA 70803USA

Four types of nanoparticles,amorphous carbon,ironⅢoxide,SiO2,and amino-coated SiO2,were tested to determine changes in tetrahydrofuran-water(THF-water)clathrate hydrate nucleation and *** were experimentally found to determine their viability for preventing natural gas hydrates from developing during offshore drilling ***-water clathrates were chosen as a model to represent gas hydrate growth at atmospheric *** of each nanoparticle between 0.15%and 1.0%by weight were tested as a kinetic inhibitor to hydrate *** were repeated at various temperatures below the formation temperature of 4.4℃for THF-water clathrate *** were made to identify how the concentration of THF affects the clathrate hydrates forming under static conditions between20%and 30%by mole of *** primary tests in this study were performed using a 20:80 THF/water *** increases during hydrate nucleation for THF-water were measured between-5 and 3℃.The range of ideal nanoparticle concentrations was found to be between 0.15%and 0.45%by weight for optimal static,kinetic inhibition of hydrate *** approximately 0.3%by weight,the most significant inhibition was observed under static conditions for all four types of nanoparticles *** found that functionalized amino-coated SiO2 nanoparticles,across all tests,significantly increased the time required for the formation of THF-water clathrate hydrates compared to the other three non-functionalized *** amorphous carbon and ironⅢoxide nanoparticles performed similarly across each test and were both the least effective in their inhibition of the clathrate hydrates of the four nanoparticles studied compared to a control.

关键词： Nanoparticles Gas hydrates Clathrates Hydrate inhibition Functionalized nanoparticles

宫颈癌内外照射后放射性直肠损伤临床预测模型的研究

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中华放射医学与防护杂志 2024年第2期44卷 119-126页

作者：陈宝杰曹璐余远航赵强谢杉沙杜丹李贤富川北医学院附属医院肿瘤科南充637000 川北医学院临床医学院南充637000 医学影像四川省重点实验室四川省肿瘤学重点学科南充637000

目的探讨宫颈癌内外照射放疗不同剂量叠加方式的剂量学差异,建立宫颈癌放疗后慢性放射性直肠损伤(RLRI)的临床预测模型。方法回顾性分析2020年1月1日至2021年11月30日于川北医学院附属医院肿瘤科接受根治性同步放化疗宫颈癌患者的临床资... 详细信息

目的探讨宫颈癌内外照射放疗不同剂量叠加方式的剂量学差异,建立宫颈癌放疗后慢性放射性直肠损伤(RLRI)的临床预测模型。方法回顾性分析2020年1月1日至2021年11月30日于川北医学院附属医院肿瘤科接受根治性同步放化疗宫颈癌患者的临床资料,放疗采用外照射+近距离治疗方式,内外照射剂量评估采用内、外照射生物等效剂量(EQD2)参数直接叠加和内外照射三维计划图像形变配准(DIR)剂量叠加,分析两种剂量评估方式剂量学差异。RLRI分级标准采用肿瘤放射治疗协作组标准。运用两种剂量评估方式构建RLRI的预测模型,使用受试者工作特征(ROC)曲线计算曲线下面积,以评估不同剂量评估方式的预测准确性。结果多次近距离治疗剂量叠加的EQD2参数较DIR剂量叠加高危临床靶区D95%和D90%分别高2.18和2.92 Gy,直肠D_(2 cm)3、D_(1 cm)3、D_(0.1 cm)3分别高1.74、2.28、2.26 Gy(t=3.82、5.21、4.58、5.17、2.05,P0.05)。传统预测指标DIR剂量叠加的预测模型:直肠D_(2 cm)3、D_(1 cm)3的ROC曲线下面积分别为0.784、0.763,最佳预测阈值的灵敏度分别为0.850、0.750,特异度分别为0.679、0.717。结论内外照射EQD2参数直接叠加与三维计划图进行DIR剂量叠加评估剂量参数有剂量学差异。DIR剂量叠加直肠D_(2 cm)3、D_(1 cm)3与联合预测模型预测RLRI的价值较高,但联合预测模型预测RLRI计算复杂,建议临床上通过DIR剂量叠加直肠D_(2 cm)3、D_(1 cm)3预测RLRI。

关键词：宫颈癌形变图像配准放射性直肠损伤临床预测模型

Response of soil respiration to environmental and photosynthetic factors in different subalpine forest-cover types in a loess alpine hilly region

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Journal of Forestry Research 2022年第2期33卷 653-665页

作者： yuanhang Li Sha Lin Qi Chen Xinyao Ma Shuaijun Wang Kangning He School of Soil and Water Conservation Key Laboratory of State Forestry Administration On Soil and Water ConservationBeijing Forestry UniversityBeijing 100083People’s Republic of China Beijing Engineering Research Center of Soil and Water Conservation Beijing Forestry UniversityBeijing 100083People’s Republic of China Engineering Research Center of Forestry Ecological Engineering Ministry of EducationBeijing Forestry UniversityBeijing 100083People’s Republic of China North China Power Engineering Co. Ltd.of China Power Engineering Consulting GroupChangchun 130021People’s Republic of China Power China Huadong Engineering Corporation Limited Hangzhou 311122People’s Republic of China

Soil respiration(Rs)is important for transport-ing or fixing carbon dioxide from the atmosphere,and even diminutive variations can profoundly influence the carbon ***,the R_(s) dynamics in a loess alpine hilly region with representative sensitivity to climate change and fragile ecology remains poorly *** study investigated the correlation and degree of control between R_(s) and its photosynthetic and environmental factors in five subalpine forest cover *** examined the correlations between R_(s) and variables temperature(T_(10)) and soil moisture content at 10 cm depth(W_(10)),net photosynthetic rate(P_(n))and soil properties to establish multiple models,and the variables were measured for diurnal and monthly vari-ations from September 2018 to August *** results showed that soil physical factors are not the main drivers of R_(s) dynamics at the diel scale;however,the trend in the monthly variation in R_(s) was consistent with that of T_(10)and P_(n).Further,R_(s) was significantly affected by pH,providing further evidence that coniferous forest leaves contribute to soil acidification,thus reducing R_(s).Significant exponential and linear correlations were established between R_(s) and T_(10)and W_(10),respectively,and R_(s) was positively correlated with P_(n).Accordingly,we established a two-factor model and a three-factor model,and the correlation coefficients(R_(2))was improved to different degrees compared with models based only on T_(10) and W_(10).Moreover,temperature sensitivity(Q_(10))was the highest in the secondary forest and lowest in the Larix principis-rupprechtii *** findings suggest that the control of R_(s) by the environment(moisture and tempera-ture)and photosynthesis,which are interactive or comple-mentary effects,may influence spatial and temporal homeo-stasis in the region and showed that the models appropriately described the dynamic variation in R_(s) and the carbon cycle in different forest *** add

关键词： Loess alpine hilly region Soil respiration Environmental factor Photosynthesis factor Q_(10) Two-factor model Three-factor model

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高强不锈钢筋UHPC梁受弯性能试验研究

建筑科学 2024年第1期40卷 93-100页

作者：李海云韩金良李然王远航赵晶黄群广石家庄铁道大学河北石家庄050043 广州地铁设计研究院股份有限公司广东广州510000 中国铁建大桥工程局集团有限公司天津300300

本次试验设计了6根超高性能混凝土(Ultra-High Performance Concrete,UHPC)梁,4根配置双相体不锈钢筋、1根配置奥氏体不锈钢筋、1根配置普通钢筋作为对照组,通过三分点加载的方式对梁进行受弯试验。通过钢筋直径、钢筋种类、截面尺寸等... 详细信息

本次试验设计了6根超高性能混凝土(Ultra-High Performance Concrete,UHPC)梁,4根配置双相体不锈钢筋、1根配置奥氏体不锈钢筋、1根配置普通钢筋作为对照组,通过三分点加载的方式对梁进行受弯试验。通过钢筋直径、钢筋种类、截面尺寸等参数的变化来研究高强不锈钢筋UHPC梁的承载力的变化。通过试验发现,UHPC梁在配置双相体不锈钢筋时比配置普通钢筋时在承载力上有所提升。配置奥氏体不锈钢筋的梁比配置双相体不锈钢筋的梁在承载力方面也有一定程度提升。随着配筋率增加可减缓裂缝的发展速度,根据平截面假定、UHPC与不锈钢筋的应力-应变关系式提出了不锈钢筋UHPC梁受弯承载力表达式,可以较好地反映梁受弯性能。引入了最大裂缝宽度修正系数,经修正的最大裂缝宽度计算式可较准确地计算不锈钢筋UHPC梁的最大裂缝宽度。

关键词：高强不锈钢筋超高性能混凝土受弯承载力裂缝宽度

Source apportionment and secondary organic aerosol estimation of PM_(2.5) in an urban atmosphere in China

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Science China Earth Sciences 2014年第4期57卷 1352-1362页

作者： HUANG XiaoFeng YUN Hui GONG ZhaoHeng LI Xiang HE LingYan ZHANG yuanhang HU Min Key Laboratory for Urban Habitat Environmental Science and Technology School of Environment and Energy Peking University Shenzhen Graduate School State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking University

PM2.5 is the key pollutant in atmospheric pollution in *** new national air quality standards taking effect,PM2.5 has become a major issue for future pollution *** effectively prevent and control PM2.5,its emission sources must be precisely and thoroughly ***,there are few publications reporting comprehensive and systematic results of PM2.5 source apportionment in the *** on PM2.5 sampling during 2009 in Shenzhen and follow-up investigation,positive matrix factorization(PMF)analysis has been carried out to understand the major sources and their temporal and spatial *** results show that in urban Shenzhen(University Town site),annual mean PM2.5 concentration was 42.2μg m?3,with secondary sulfate,vehicular emission,biomass burning and secondary nitrate as major sources;these contributed30.0%,26.9%,9.8%and 9.3%to total PM2.5,*** sources included high chloride,heavy oil combustion,sea salt,dust and the metallurgical industry,with contributions between 2%–4%.Spatiotemporal variations of various sources show that vehicular emission was mainly a local source,whereas secondary sulfate and biomass burning were mostly *** nitrate had both local and regional *** of secondary organic aerosol(SOA)has always been difficult in aerosol source *** this study,the PMF model and organic carbon/elemental carbon(OC/EC)ratio method were combined to estimate SOA in *** results show that in urban Shenzhen,annual SOA mass concentration was 7.5μg m?3,accounting for 57%of total organic matter,with precursors emitted from vehicles as the major *** work can serve as a case study for further in-depth research on PM2.5 pollution and source apportionment in China.

关键词： PM2.5 source apportionment secondary organic aerosol(SOA)

耕地后备资源研究进展与趋势——基于CiteSpace文献计量分析

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安徽农学通报 2024年第9期30卷 130-137页

作者：先远航黄星王佑汉廖琴西华师范大学地理科学学院四川南充637009 丘陵地区国土资源统筹利用工程实验室四川南充637009 中国农业大学经济管理学院北京100083

耕地后备资源开发是实行耕地保护和耕地占补平衡的重要保障之一。本文利用CiteSpace软件系统分析耕地后备资源研究领域的现状与脉络,明晰未来发展趋势。结果表明,耕地后备资源研究聚焦于农业资源保护开发与土地规划利用研究,小范围内学... 详细信息

耕地后备资源开发是实行耕地保护和耕地占补平衡的重要保障之一。本文利用CiteSpace软件系统分析耕地后备资源研究领域的现状与脉络,明晰未来发展趋势。结果表明,耕地后备资源研究聚焦于农业资源保护开发与土地规划利用研究,小范围内学术合作联系紧密,跨区域合作交流较少。“适宜性评价”“土地开发”和“占补平衡”等为主要研究热点。研究发展历程分为萌芽探索、波动发展和平稳成熟3个阶段。土地潜力评价与开发保护研究贯穿发展历程,前沿发展主要集中在全域土地综合整治,加强土地改造利用技术研究,坚持生态可持续与高质量发展等方面。未来研究应加强边际土地潜力挖掘,深化开发评价、理论体系构建,强化地理信息技术应用与生态修复技术研究,积极探索通过土地整治实现国土空间治理与粮食安全的有效途径。

关键词：耕地后备资源 CiteSpace 适宜性评价土地开发占补平衡文献计量学

维普期刊数据库博看期刊

改进混合粒子群算法求解带时间窗的无人机与车辆协同路径调度问题

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计算机应用研究 2024年第8期41卷 2336-2342页

作者：叶立威吴钧皓戚远航罗浩宇黄戈文王福杰电子科技大学中山学院计算机学院广东中山528402 广东工业大学自动化学院广州510006 嘉应学院信息网络中心广东梅州514015 东莞理工学院卓越工程师学院广东东莞523808

为提高物流配送效率,考虑时间窗、无人机换电以及无人机多点连续配送等因素,提出了一种带时间窗的车辆与无人机协同配送问题,并设计一种带局部搜索的混合粒子群算法进行求解。该算法以混合粒子群算法为核心,通过构建高效的编解码策略实... 详细信息

为提高物流配送效率,考虑时间窗、无人机换电以及无人机多点连续配送等因素,提出了一种带时间窗的车辆与无人机协同配送问题,并设计一种带局部搜索的混合粒子群算法进行求解。该算法以混合粒子群算法为核心,通过构建高效的编解码策略实现了问题解空间到算法搜索空间的转换。进一步,该算法融合单点插入策略、车辆更换策略、无人机更换策略组成局部搜索策略,以此提高算法寻优能力。实验结果表明:所提模型比纯车辆配送的模型效率更高,节省了31.51%的成本;所提算法优于四种对比算法,优化率最高达到82.08%。

关键词：无人机车辆调度粒子群时间窗车辆路径问题

The influence of charge characteristics of suspension droplets on the ion flow field in different temperatures and humidity

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Plasma Science and Technology 2022年第4期24卷 29-36页

作者： Nanxuan SHEN Zihan SU yuanhang ZHANG Tiebing LU State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206People's Republic of China

In order to clarify the charging characteristics of suspension droplets in ion flow field under different temperatures and humidity,the effective charging factor used to characterize the charging characteristics of suspension droplets is introduced in this paper,and a calculation method of charging factor is proposed based on the upstream finite element method(FEM).Then,the charging factor under different temperatures and humidity is calculated,and the analytic expression of the charging factor considering the influence of temperature and humidity is obtained by fitting the calculation *** influence of suspension droplets on the ion flow field is *** results show that the charging factor is small and increases little with the relative humidity when the relative humidity is less than 60%,and the charging factor is large and increases rapidly with the relative humidity when the relative humidity is more than 60%.At the same relative humidity,the charging factor increases linearly with the *** influence of charged suspension droplets on the ion flow field can be ignored when the relative humidity is less than 60%and must be considered under high temperature and *** calculation method and analytic expression of the charging factor proposed in this paper can be used to model of ion flow field considering the influence of temperature and humidity and provide technical support for the construction of HVDC transmission lines across high temperature and humidity.

关键词： suspension droplets charging characteristics humidity temperature ion flow field

DEGRADATION OF ORGANIC POLLUTANTS IN FLOCCULATED LIQUID DIGESTATE USING PHOTOCATALYTIC TITANATE NANOFIBERS: MECHANISM AND RESPONSE SURFACE OPTIMIZATION

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Frontiers of Agricultural Science and Engineering 2023年第3期10卷 492-502页

作者： Yiting XIAO Yang TIAN yuanhang ZHAN Jun ZHU Department of Biological and Agricultural Engineering University of ArkansasFayettevilleAR 72701USA Material Science and Engineering Programs University of ArkansasFayettevilleAR 72701USA

Titanate nanofibers(TNFs)were synthesized using a hydrothermal method and were employed for the first time in this study to photocatalytically degrade organic pollutants found in flocculated liquid digestate of poultry *** photocatalytic performance of TNFs,with a bandgap of 3.16 eV,was tested based on degradation of organic pollutants and removal of *** combinations of pollutant concentration and pH were examined(0.2 to 1.3 g·L^(−1) at pH 4 to 10).Central composite design(CCD)and response surface methodology(RSM)were applied in order to optimize the removal rates of volatile fatty acids(VFA)and chemical oxygen demand(COD),and the decolorization *** were no significant differences between the regression models generated by the CCD/RSM and the experimental *** was found that the optimal values for pH,dosage,VFA removal rate,COD removal rate and decolorization rate were 6.752,0.767 g·L^(−1),72.9%,59.1%and 66.8%,*** findings indicates that photocatalytic TNFs have potential for the posttreatment of anaerobic digestion effluent,as well as other types of wastewater.

关键词： titanate nanofibers photocatalysis poultry litter liquid digestate