钢-混凝土组合连续梁桥动力响应试验研究   总被引：1，自引：0，他引：1  

郑则群  房贞政 《地震工程与工程振动》2006,26(4):175-181

钢-混凝土组合梁桥动力响应有其特点,本文结合福州光明港钢-混凝土组合连续梁桥实际工程,开展环境激励及汽车动载激励试验,并应用有限元进行分析和研究,表明理论计算与实测的频率和振型等动力特性较吻合,同时进行组合作用、横向支撑连接、体外预应力等参数研究,为该类型组合连续梁桥的动力性能研究与工程设计提供参考。  相似文献   

西宁市城区扩展对比中遥感影像处理技术的探讨     

韩丽蓉  韩玉蓉 《测绘与空间地理信息》2007,30(4):45-47

根据西宁市城区扩展监测对遥感信息提取的需要,采用多种方法将具有较高空间分辨率的SPOT遥感图像和具有多波谱的ETM 遥感图像进行增强及融合试验,结果表明:对ETM 影像先进行锐化处理,再将SPOT影像与锐化后的ETM 信息融合,然后对融合后的影像进行去霾处理得到的影像质量最好。  相似文献   

桩-网路堤位移应力分析及其应用     

潘学政  吴明  陈汉良 《海洋学研究》2007,25(2):57-62

由于桩-网复合地基的结构形式比较复杂,难以采用解析法求得其应力和位移。利用有限差分法对某桩-网法路堤进行了数值模拟,并取得了较好结果。计算结果显示,桩间土沉降线为悬链线,与现场位移监测结果吻合较好;桩身弯矩和桩土应力反映了桩-网复合地基的一些受力机理。分析认为,桩间土沉降较大的主要原因是由土体本身压缩及桩侧弯引起的。  相似文献   

羧乙基壳聚糖蒙脱石吸附养殖水体中Cu²⁺的应用     

李俭平  周忻宇  代婧炜  沈庆洲 《海洋科学》2020,44(2):120-130

为了寻求性能良好、环保吸附剂,用于去除养殖水体中重金属Cu~(2+),作者利用蒙脱石负载羧乙基壳聚糖制备成复合吸附剂,并利用IR、SEM、XRD等手段分析其表面性能,将其用于处理Cu~(2+)溶液,考察了环境因子对其吸附性能的影响,并从吸附动力学和吸附热力学角度分析吸附剂对Cu~(2+)的吸附机理,最后考察其再生利用效果。结果表明:羧乙基壳聚糖成功进入到蒙脱石层间;在羧乙基壳聚糖与蒙脱石质量比为1︰25、40℃恒温水浴搅拌60min、pH=6.0、最佳投加量为4.0g/L、处理浓度不超过30 mg/L Cu~(2+)溶液时,复合吸附剂对Cu~(2+)去除率可以达到96.23%,将其用于淡水养殖鱼塘水体中, Cu~(2+)去除后可达到《渔业水质标准》规定;吸附剂对Cu~(2+)吸附热力学实验结果表明,符合Langmuir模型,反应过程为自发、吸热反应;吸附动力学结果表明该吸附符合准二级动力学方程,反应属于化学吸附;再生实验中NaOH的再生效果优于HCl。  相似文献   

Ecosystem carbon storage under different scenarios of land use change in Qihe catchment,China   总被引：1，自引：1，他引：0  

Zhu  Wenbo  Zhang  Jingjing  Cui  Yaoping  Zhu  Lianqi 《地理学报(英文版)》2020,30(9):1507-1522

Regional land use change is the main cause of the ecosystem carbon storage changes by affecting emission and sink process.However,there has been little research on the influence of land use changes for ecosystem carbon storage at both temporal and spatial scales.For this study,the Qihe catchment in the southern part of the Taihang Mountains was taken as an example;its land use change from 2005 to 2015 was analyzed,the Markov-CLUE-S composite model was used to predict land use patterns in 2025 under natural growth,cultivated land protection and ecological conservation scenario,and the land use data were used to evaluate ecosystem carbon storage under different scenarios for the recent 10-year interval and the future based on the carbon storage module of the In VEST model.The results show the following:(1) the ecosystem carbon storage and average carbon density of Qihe catchment were 3.16×107 t and 141.9 t/ha,respectively,and decreased by 0.07×107 t and 2.89 t/ha in the decade evaluated.(2) During 2005–2015,carbon density mainly decreased in low altitude areas.For high altitude area,regions with increased carbon density comprised a similar percentage to regions with decreased carbon density.The significant increase of the construction areas in the middle and lower reaches of Qihe and the degradation of upper reach woodland were core reasons for carbon density decrease.(3) For 2015–2025,under natural growth scenario,carbon storage and carbon density also significantly decrease,mainly due to the decrease of carbon sequestration capacity in low altitude areas;under cultivated land protection scenario,the decrease of carbon storage and carbon density will slow down,mainly due to the increase of carbon sequestration capacity in low altitude areas;under ecological conservation scenario,carbon storage and carbon density significantly increase and reach 3.19×107 t and 143.26 t/ha,respectively,mainly in regions above 1100 m in altitude.Ecological conservation scenario can enhance carbon sequestration capacity but cannot effectively control the reduction of cultivated land areas.Thus,land use planning of research areas should consider both ecological conservation and cultivated land protection scenarios to increase carbon sink and ensure the cultivated land quality and food safety.  相似文献   

滤食性贝类在对虾综合养殖生态系统中的作用   总被引：6，自引：0，他引：6  

吴桂汉  陈品健  江瑞胜 《台湾海峡》2001,20(4):447-452

就混养虾池中滤食性贝类如何影响虾池整个生态系统这个问题，综合了国内外这方面的文献，从滤食性贝类对混养虾池的水质、底质和其中的浮游植物、浮游动物的影响，以及混养对养殖效益的影响这几个方面作了探讨。  相似文献   

海水中液-固界面的台阶型动力学曲线 Ⅱ.液膜扩散-递进扩散-界面分级交换反应联合控制的复合模型理论     

刘莲生  张正斌  蔡卫君  潘纲  杜恒清 《海洋与湖沼》1993,24(5):477-484

为定量解释海水中液-固界面的台阶型动力学曲线及其台阶的消长变化规律,在我们已提出的“液膜扩散和递进液膜扩散控制的复合模型”和“海水中液-固界面分级离子/配位子交换理论”基础上,吸取Crank的若干数学处理方法,进而提出适合于非稳态体系的“液膜扩散-递进扩散-界面分级交换反应联合控制的复合模型”。  相似文献   

Damage assessment for submarine photoelectric composite cable under anchor impact     

《Applied Ocean Research》2018

The impact of dropped anchor on submarine photoelectric composite cables may possibly cause electrical faults, i.e. electricity and optical signal transmission failure. In order to study the impact capacity and structural impact failure mechanism, a test setup is designed originally to examine the structural and functional integrity. A detailed finite element model (FEM) is created, considering material nonlinearity and component interaction. A parametric analysis has been performed to predict the deformation of components and impact forces, under different impact velocities and collision directions. Relationships between the armor layer indentation rate and that of internal power and optical units are achieved. The impact deformation of internal entities can be evaluated intuitively by armor layer indentation. The proposed experimental and numerical methods are well correlated, suitable to assess the impact capacity of subsea power cables and assist the protection design of subsea power cables in engineering.  相似文献   

Google Earth Engine平台支持下的赣南柑橘果园遥感提取研究   总被引：1，自引：0，他引：1  

徐晗泽宇  刘冲  王军邦  齐述华 《地球信息科学学报》2018,20(3):396-404

赣南地区是中国柑橘主产区,柑橘种植产业经数十年发展已具较大规模。本文利用Google Earth Engine平台,使用2140景Landsat影像进行像元级融合,重构目标年份季节最小云量影像集,构建多维分类特征集,利用随机森林分类算法,实现了1990、1995、2000、2005、2010和2016年赣南柑橘果园的分布制图。结果表明：利用Google Earth Engine平台可实现大量遥感影像数据的高效处理;最小云量影像合成方法能够有效解决多云多雨地区高质量光学影像获取困难的问题;以最小云量影像合成构建的数据集,使用随机森林分类算法能够有效提取赣南柑橘果园,分类平均总体精度和Kappa系数分别为93.15%和0.90,分类效果良好;赣南柑橘果园面积由1990年9.77 km²扩大为2016年2200.34 km²,2005年以后呈大规模扩张趋势,果园分布由零星分布,逐步形成连片化的聚集分布特点,柑橘果园用地的主要来源为林地、灌丛和耕地。  相似文献   

Molecular and isotopic compositions of bitumens in Silurian tar sands from the Tarim Basin,NW China: Characterizing biodegradation and hydrocarbon charging in an old composite basin   总被引：1，自引：0，他引：1  

Wanglu Jia  Zhongyao Xiao  Chiling Yu  Ping'an Peng 《Marine and Petroleum Geology》2010

Biodegradation and oil mixing in Silurian sandstone reservoirs of the Tarim Basin, one of the largest composite basins in China, were investigated by analyzing the molecular characteristics and stable carbon isotopic signatures of low-molecular-weight (LMW) saturated hydrocarbons and high-molecular-weight (HMW) asphaltenes. Detection of 25-norhopanes and 17-nortricyclic terpanes in most Silurian tar sands from the Tabei Uplift in the Tarim Basin suggests a much greater degree of biodegradation here than in the Tazhong Uplift. This explains the relatively more abundant tricyclic terpanes, gammacerane, pregnane and diasteranes in tar sands from the Tabei Uplift than in those from the Tazhong Uplift. Hence, care must be taken when assigning oil source correlations using biomarkers in tar sands because of the biodegradation and mixing of oils derived from multiple sources in such an old composite basin. Asphaltenes in the tar sands seem to be part of the oil charge before biodegradation, depending on the relative anti-biodegradation characteristics of asphaltenes, the similarity in carbon isotopic signatures for asphaltenes and their pyrolysates, and the consistent product distribution for flash pyrolysis and for regular steranes in asphaltene pyrolysates, regardless of whether the tar sands were charged with fresh oil. According to the relative distributions of regular steranes and the relatively abundant 1,2,3,4-tetramethylbenzene significantly enriched in ¹³C, the oil sources for asphaltenes in the tar sands might be related to lower Paleozoic marine source rocks formed in euxinic conditions. Nevertheless, the relatively low abundance of gammacerane and C₂₈ regular steranes observed in asphaltene pyrolysates and residual hydrocarbons, within limited samples investigated in this work, made a direct correlation of oils originally charged into Silurian tar sands with those Cambrian source rocks, reported so far, seem not to be possible. Comparison of carbon isotopic signatures of n-alkanes in asphaltene pyrolysates with those of LMW saturated hydrocarbons is helpful in determining if the abundant n-alkanes in tar sands are derived from fresh oil charges after biodegradation. The limited carbon isotopic data for n-alkanes in LMW saturated hydrocarbons from the tar sands can be used to classify oils charged after biodegradation in the composite basin into four distinct groups.  相似文献