检索结果-南通市图书馆

基于人工神经网络的RC框架结构地震响应预测方法

在线全文

学校读者我要写书评

暂无评论

地震研究 2024年第1期47卷 123-134页

作者：赵煜东许卫晓于德湖邱玲玲陈阵隆邱玉胜青岛理工大学土木工程学院山东青岛266520 山东建筑大学土木工程学院山东济南250101 青岛中建联合集团有限公司山东青岛266100 青岛市博物馆山东青岛266061

为了实现钢筋混凝土(Reinforced Concrete,RC)框架结构地震响应的快速预测,提出了一种基于人工神经网络的RC框架结构地震响应预测方法,设计低层、多层和小高层共3个典型RC框架结构作为研究对象,以四川雅安地区为目标场地,基于条件均值... 详细信息

为了实现钢筋混凝土(Reinforced Concrete,RC)框架结构地震响应的快速预测,提出了一种基于人工神经网络的RC框架结构地震响应预测方法,设计低层、多层和小高层共3个典型RC框架结构作为研究对象,以四川雅安地区为目标场地,基于条件均值谱选取地震动记录作为输入并进行弹塑性时程分析,所得样本数据用于训练人工神经网络。以地震动强度信息和结构信息为输入预测结构响应,同时对模型进行参数敏感性分析。结果表明:建立的人工神经网络模型具有较好的泛化性能,平均谱加速度具有最高的平均影响值,提出的方法为快速预测RC框架结构地震响应提供了方法借鉴。

关键词： RC框架结构人工神经网络地震响应参数敏感性分析

维普期刊数据库博看期刊

Distribution of radium-224 in the western Arctic Ocean

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2005年第6期24卷 109-116页

作者： qiu yusheng CHEN Min LI Yanping Department of Oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China Department of Oceanography Xiamen University Xiamen 361005 China

Radium-224 activities in the western Arctic Ocean were measured viaship-board ^(220)Rn emanation technique during the Second Chinese National Arctic Expedition. Theresults showed that the ^(224)Ra activities in the study areas ranged from being less than 0.08 to3.58 Bq/m^3, with an average of 0.23 Bq/m^3. The low ^(224)Ra concentration in the surface water wasattributed to the influence of sea ice melted water. The horizontal distribution of surface^(224)Ra in the western Arctic Ocean showed a high ^(224)Ra characteristics occurred along the slopearound 160°W, providing evidence for the importance of ice-rafted sediments to controlling thedistribution of radium isotopes in the Arctic Ocean. Mostly, ^(224)Ra concentrations increased withthe depth in the shelf region and reached a maximum at 75 m at the central Canada Basin, whichfurther confirms the importance of the transport of shelf bottom water to maintaining the upperhalocline layer in the Canada Basin.

关键词： ^(224)Ra distribution western arctic ocean

Adsorption of Th and Pa onto particles and the effect of organic compounds in natural seawater

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2021年第6期39卷 2209-2219页

作者： Xinxing ZHANG Weifeng YANG yusheng qiu Minfang ZHENG College of Ocean and Earth Sciences Xiamen UniversityXiamen 361102China North China Sea Environmental Monitoring Center State Oceanic AdministrationQingdao 266033China State Key Laboratory of Marine Environmental Science Xiamen 361102China

^(231)Pa and ^(230)Th are two crucial isotopes in the ongoing GEOTRACES ***,the controversy on ^(231)Pa/^(230)Th proxy pertaining to archiving ocean circulation or recording paleoproductivity,is still unresolved,partly owing to the unclear understanding of fractionation between ^(231)Pa and ^(230)Th during *** this study,controlled experiments were conducted to examine the adsorption of ^(234)Th and ^(233)Pa onto biogenic particles(SiO_(2) and CaCO_(3)),authigenic minerals(MnO_(2) and Fe_(2)O_(3)),and lithogenic minerals(kaolinite,attapulgite,montmorillonite,and aluminum oxyhydroxides),and the role of organic compounds in regulating the adsorption of ^(234)Th and ^(233)Pa in natural seawater was *** distribution coefficients(K d,presented as logK_(d))varied from 3.56 to 6.05 and from 3.27 to 5.82 for ^(234)Th and ^(233)Pa,***_(2)O_(3) is the strongest sorbent for both ^(234)Th and ^(233)*** of the particles showed comparable logK_(d) values for either ^(234)Th(~4.8)or ^(233)Pa(~3.9)in the presence of dextran,indicating that the adsorption of Th and Pa is likely controlled by organic coating on particle *** fractionation factors(F Th/Pa)of SiO_(2)(3±1)and CaCO_(3)(33±1)suggest in situ observed preferential scavenging of ^(230)Th to ^(231)Pa in the surface water of low-to mid-latitude regions and the nearly equal removal in the Antarctic Ocean where biogenic silica dominates the particle *** F Th/Pa values of the lithogenic and biogenic particles indicate that ^(230)Th is scavenged prior to ^(231)Pa in the particle-scarce ocean *** equal scavenging of ^(230)Th and ^(231)Pa at the ocean margins and the ridge crests is dominated by high particle fl uxes instead of particle composition *** results imply that ^(230)Th/^(231)Pa can be used as different proxies in different oceanic settings.

关键词： thorium protactinium paleoproductivity circulation particle dynamics

Regional estimates of POC export flux derived from thorium-234 in the western Arctic Ocean

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2005年第6期24卷 97-108页

作者： MA Qiang CHEN Min qiu yusheng LI Yanping Department of Oceanography Xiamen University Xiamen 361005 China Department of Oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China Department of Oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China

In order to elucidate the regional export variation of participate organiccarbon in the western Arctic Ocean, samples vertically integrated between 0 and 100 m depth orbetween 0 and 30 m/40 m depth were collected for total ^(234)Th measurements and those from 30 m/40m or 100 m depth were collected for paniculate ^(234)Th measurements during the Second ChineseArctic Expedition in July— September 2003. The removal fluxes and residence time of ^(234)Th in theupper water column were calculated by using irreversible steady-state scavenging model. The resultsshowed that, total ^(234)Th was deficit relative to its parent ^(238)U in the western Arctic Oceanexcept in the western Chukchi shelf and the slope regions around 160°W, indicating that scavengingand removal processes play an important role in element biogeochemical cycle in the Arctic Ocean. Inthe western Chukchi shelf and the slope regions around 160°W, total ^(234)Th was excess relativeto ^(238)U, ascribing to the horizontal input of ^(234)Th adsorbed by ice-rafted ***-234 removal fluxes decreased from the shelf to the deep ocean, while the residence time of^(234)Th increased from shelf to offshore, demonstrating that particle scavenging and removalprocesses are more active in the shelf regions. The estimated POC export fluxes from 40 m in theshelf regions and from 100 m in the slope and deep ocean varied between 1.6 and 27.5 mmol/(m^2·d),and between 1.8 and 14.4 mmol/(m^2·d), respectively. The averaged POC export fluxes over the entirewater column decreased from the shelf to the deep ocean, indicating that the Chukchi shelf is animportant region for organic carbon sequestration. The high ThE ratios (ratio of POC export fluxderived from ^(234)Th/^(238)U disequilibria to primary production) in the western Arctic Oceansuggested that the biological pump runs actively in high-latitudes.

关键词： POC export flux ^(234)Th western arctic ocean

Utilizing ^(234)Th/^(238)U disequilibrium to constrain particle dynamics in hydrothermal plumes in the Southwest Indian Ocean

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2021年第6期40卷 16-25页

作者： Weifeng Yang Xinxing Zhang Min Chen Ziming Fang yusheng qiu State Key Laboratory of Marine Environmental Science Xiamen UniversityXiamen 361102China College of Ocean and Earth Sciences Xiamen UniversityXiamen 361102China North China Sea Environmental Monitoring Center State Oceanic AdministrationQingdao 266033China Department of Ocean Science Hong Kong University of Science and TechnologyHong Kong 999077China

Metal-enriched minerals have been widely observed near hydrothermal vent ***,the dynamics of particulate metals influenced by hydrothermal activities is poorly ***,radioactive 234Th in both dissolved and particulate phases were used to examine the kinetics of particle-reactive metal adsorption,removal,and residence in a newly found hydrothermal plume over the Southwest Indian *** results showed a relatively low value on ^(234)Th/^(238)U ratios(i.e.,0.73-0.88)compared to the deep oceans,indicating an enhanced adsorption of particle-reactive metals onto particulate matter in the *** on the 234Th-238U disequilibria,the adsorption and sinking rate constants of 234Th averaged(0.009±0.001)d^(-1) and(0.113±0.024)d^(-1) in the hydrothermal plume,corresponding to the residence times of(115±19)d and(16±5)d for dissolved and particulate 234Th,*** timescale allows vent-discharged particle-reactive metals to disperse hundreds to thousands of miles ***,hydrothermal activities might influence the metal distribution in deep ocean over a very large ***,a high sinking flux of(36.2±5.4)B q/(m^(2)·d)for 234Th was observed for the plume,suggesting an enrichment of metal in particles deposited close to the *** enhancement of particle sinking could also benefit the transport of organic carbon and nitrogen and fuel the benthic ecosystems under the plume ***,hydrothermal plumes may have an impact on both the elemental geochemistry and/or ecosystem to the deep oceans interior than previous expectation.

关键词： thorium-234 particle dynamics hydrothermal plume Indian Ocean

Insights into the coupling of upper ocean-benthic carbon dynamics in the western Arctic Ocean from an isotopic(^(13)C, ^(234)Th) perspective

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2015年第6期34卷 26-33页

作者： ZHANG Run CHEN Min MA Qiang CAO Jianping qiu yusheng College of Ocean and Earth Sciences Xiamen University State Key Laboratory of Marine Environmental Science Xiamen University

The coupling of upper ocean-benthic carbon dynamics in the ice-free western Arctic Ocean （the Chukchi Sea and the Canada Basin） was evaluated during the late July-early September 2003 using natural stable （13C） and radioactive （238U-234Th） isotope tracers. POC export flux estimated from 234Th/238U disequilibria and dissolved CO2 concentration （[CO2（aq）]） pointed out that the strengthened biological pump in the Chukchi Shelf have significantly lowered [CO2（aq）] and altered the magnitude of isotopic （12C/13C） fractionation during carbon fixation in the surface ocean. Further, δ13C signatures of surface sediments （δ13Csed） are positively correlated to those of weighted δ13Cp0C in upper ocean （δ13Csed =13.64＋1.56xδ13Cpoc, r2=0.73, p〈0.01）, suggesting that the POC isotopic signals from upper ocean have been recorded in the sediments, partly due to the rapid export of particles as evidenced by low residence times of the highly particle-reactive 234Th from the upper water column. It is suggested that there probably exists an upper ocean-benthic coupling of carbon dynamics, which likely assures the sedimentary δ13C record an indicator of paleo-CO2 in the western Arctic Ocean.

关键词： δ13C POC sediment carbon export flux western Arctic Ocean

The mean residence time of river water in the Canada Basin

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第5期53卷 777-783页

作者： CHEN Min XING Na HUANG YiPu qiu yusheng Department of Oceanography Xiamen University Xiamen 361005 China State Key Laboratory of Marine Environmental Science Xiamen University Xiamen 361005 China

Seawater was collected from the western Arctic Ocean for measurements of 18O, 226Ra and 228Ra. The fractions of river runoff and sea ice melt-water in water samples were estimated by using δ18O-S-PO* tracer system. The mean residence time of river water in the Canada Basin was calculated based on the relationship between 228Ra/226Ra)A.R. and the fractions of river runoff in the shelf and deep ocean. Our results showed that the river runoff fractions in the Canada Basin were significantly higher than those in the shelf regions, suggesting that the Canada Basin is a major storage region for Arctic river water. 228Ra activity concentrations in the Chukchi shelf and the Beaufort shelf ranged from 0.16 to 1.22 Bq/m3, lower than those reported for shelves in the low and middle latitudes, indicating the effect of sea ice melt-water. A good positive linear relationship was observed between 228Ra/226Ra)A.R. and the fraction of river runoff for shelf waters, while the 228Ra/226Ra)A.R. in the Canada Basin was located below this re-gressive line. The low 228Ra/226Ra)A.R. in the Canada Basin was ascribed to 228Ra decay during shelf wa-ters transporting to the deep ocean. The residence time of 5.0―11.0 a was estimated for the river water in the Canada Basin, which determined the time response of surface freshening in the North Atlantic to the river runoff into the Arctic Ocean.

关键词：北冰洋径流加拿大河水平均停留时间

Contrasting patterns of river runoff and sea-ice melted water in the Canada Basin

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2014年第6期33卷 46-52页

作者： TONG Jinlu CHEN Min qiu yusheng LI Yanping CAO Jianping College of Ocean and Earth Sciences Xiamen University State Key Laboratory of Marine Environmental Science Xiamen University

The fractions of river runoff and sea-ice melted water in the Canada Basin in summer 2003 were determined by the salinity-δ18O system. The fraction of river runoff （fR） was high in the upper 50 m of the water column and decreased with depth and latitude. The signals of the river runoffwere confined to water depths above 200 m. The total amount of river runoff in the Canada Basin was higher than that in other arctic seas, indicating that the Canada Basin is a main storage region for river runoff. The penetration depth of the sea-ice melted water was less than 50 m to the south of 78°N, while it was about 150 m to the north of 78°N. The total amount of sea-ice melted water was much higher to the north of 78°N than to the south of 78°N, indicating the sea-ice melted waters accumulated on the ice edge. The abundant sea-ice melted water on the ice edge was attributed to the earlier melted water in the southern Canada Basin and transported by the Beaufort Gyre or the reinforced melting of sea ice by solar radiation in the polynya.

关键词： freshwater Canada Basin 18O water mass

Determination of cosmogenic ^(32)P and ^(33)P in environmental samples

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2013年第6期32卷 18-25页

作者： CHEN Min YANG Zhi ZHANG Lei qiu yusheng MA Qiang HUANG Yipu College of Ocean and Earth Sciences Xiamen University State Key Laboratory of Marine Environmental Science Xiamen University

Understanding phosphorus dynamics in marine environment is of great importance, and appropriate trac- ers for phosphorus cycling in oceans are invaluable. In this study, two methods were developed for extrac- tion, purification, and determination of naturally occurring ^32p and ^33P in rainwater, marine plankton and sediments using both a low-level beta counter （LBC） and an ultra-low-level liquid scintillation spectrome- ter （LSS）. Blanks, chemical yields and counting efficiencies were quantified for both methods. The chemical purification of ^32P and ^33P separated by both procedures was validated by their decay curves. The absorber thickness of aluminum for LBC was assessed as 39.2 mg/cm2. ^32P and ^33P specific activities in some rain samples were determined by both methods and showed good consistent results. The advantage of the LSS over the LBC is apparent in its high counting efficiency and in determining samples with high concentration of stable phosphorus. However, when measuring environmental samples with low concentration of stable phosphorus, such as rainwater, both methods can be used and each has its distinct advantage.

关键词： ^32p, ^33P rainwater plankton sediments