型钢混凝土异形柱的轴压比限值研究   总被引：1，自引：0，他引：1  

赵鸿铁  陈宗平  薛建阳 《世界地震工程》2008,24(1):23-28

利用有限元数值积分法编写了型钢混凝土(SSC)异形柱轴压比限值的计算机程序,利用该程序可以计算任意荷载角、任意配钢形式的SSC异形柱的轴压比限值.对不同配钢形式、不同配钢率、不同截面尺寸、不同混凝土强度等级、不同荷载角作用下的SSC异形柱的轴压比限值进行深入分析.得出了以下主要结论:荷载角、配钢形式、截面尺寸对轴压比限值有明显影响;合理配钢的SSC异形柱的轴压比限值比钢筋混凝土(RC)异形柱有所提高;箍筋约束混凝土作用对轴压比限值有明显提高.  相似文献   

摄食水平对卵形鲳鲹幼鱼的生长和能量收支的影响     

黄建盛  陈刚  张健东  施钢  汤保贵  周晖  潘传豪 《广东海洋大学学报》2010,30(1):18-23

水温28±1℃条件下,投喂人工配合饲料,研究摄食水平1%、2%、3%、4%、5%(每日投喂量占初始实验鱼湿重的质量百分比)及饱食对卵形鲳鲹幼鱼(初始体重5.77±0.45g)生长及能量收支的影响。结果表明,卵形鲳鲹幼鱼特定生长率、转化效率、摄食率随着摄食水平的提高而增长,摄食水平达4%时干重特定生长率与饱食组差异无显著性(P>0.05),摄食水平达5%时,湿重、蛋白质和能量生长率与饱食组差异无显著性(P>0.05);摄食水平达4%时能值转化效率与饱食组差异无显著性(P>0.05),摄食水平达5%时,干重、蛋白质转化效率与饱食组差异无显著性(P>0.05);摄食水平达2%时干重、蛋白质表观效率与饱食组差异无显著性(P>0.05),摄食水平达4%时,能量表观效率与饱食组差异无显著性(P>0.05)。生长能分配率随摄食水平升高而显著增加(P<0.05),代谢能、排粪能及排泄能分配率的变化则相反。建立了6种摄食水平条件下卵形鲳鲹幼鱼的能量收支方程。  相似文献   

Évolution récente et actuelle de la côte basque française (analyse et perspectives)     

Antonin Genna  Jean-Pierre Capdeville  Jacques Dubreuilh  Cyril Mallet 《Comptes Rendus Geoscience》2005,337(16):1474

A recent multidisciplinary study, comprising existing data analysis and geomorphological and geological fieldwork, has helped clarify marine erosion processes of Pyrenean formations along the Basque Coast. An important discovery was made during our study of an alterite of regional extent, which calls into question recent and present evolution of the Basque Coast and the processes leading to coastline retreat. Modelling these factors has made it possible to propose a predictive scenario for future coastal evolution. To cite this article: A. Genna et al., C. R. Geoscience 337 (2005).  相似文献   

Quantitative evaluation of soil processes using in situ-produced cosmogenic nuclides     

Erik Thorson Brown  Fabrice Colin  Didier L. Bourls 《Comptes Rendus Geoscience》2003,335(16):1161-1171

In situ-produced cosmogenic nuclides provide a means for quantitative evaluation of a wide range of weathering and sediment transport processes. Although these nuclides have received attention for their power as geochronometers of surface exposure, it may be argued that they are more broadly suited for study of surface processes. In many environments, they may be used to evaluate collapse, erosion, burial, bioturbation, and creep, as well as providing a qualitative basis for distinguishing allochthonous from autochthonous materials. In addition, these nuclides can provide quantitative information on rates of erosion on scales of landforms and drainage basins. Here, we review the systematics of cosmogenic nuclide production within the Earth's surface, and present field examples demonstrating the utilization of in situ-produced cosmogenic nuclides distributions for evaluation of a range of soil evolution processes. To cite this article: E.T. Brown et al., C. R. Geoscience 335 (2003).  相似文献   

Iron Distribution in Size‐Resolved Aerosols Generated by UV‐Femtosecond Laser Ablation: Influence of Cell Geometry and Implications for In Situ Isotopic Determination by LA‐MC‐ICP‐MS     

Francois‐Xavier d'Abzac  Andrew D. Czaja  Brian L. Beard  James J. Schauer  Clark M. Johnson 《Geostandards and Geoanalytical Research》2014,38(3):293-309

The influence of ablation cell geometry (Frames single‐ and HelEx two‐volume cells) and laser wavelength (198 and 266 nm) on aerosols produced by femtosecond laser ablation (fs‐LA) were evaluated. Morphologies, iron mass distribution (IMD) and ⁵⁶Fe/⁵⁴Fe ratios of particles generated from magnetite, pyrite, haematite and siderite were studied. The following two morphologies were identified: spherules (10–200 nm) and agglomerates (5–10 nm). Similarity in IMD and ablation rate at 198 and 266 nm indicates similar ablation mechanisms. ⁵⁶Fe/⁵⁴Fe ratios increased with aerodynamic particle size as a result of kinetic fractionation during laser plasma plume expansion, cooling and aerosol condensation. The HelEx cell produces smaller particles with a larger range of ⁵⁶Fe/⁵⁴Fe ratios (1.85‰) than particles from the Frames cell (1.16‰), but the bulk aerosol matches the bulk substrate for both cells, demonstrating stoichiometric fs‐LA sampling. IMD differences are the result of faster wash out of the HelEx cell allowing less time for agglomeration of small, low‐δ ⁵⁶Fe particles with larger, high‐δ ⁵⁶Fe particles in the cell. Even with a shorter ablation time, half the total Fe ion intensity, and half the ablation volume, the HelEx cell produced Fe isotope determinations for magnetite that were as precise as the Frames cell, even when the latter included an aerosol‐homogenising mixing chamber. The HelEx cell delivered a more constant stream of small particles to the ICP, producing a more stable Fe ion signal (0.7% vs. 1.5% RSE for ⁵⁶Fe in a forty‐cycle single analysis), constant instrumental mass bias and thus a more precise measurement.  相似文献   

Spatial and temporal variability in feeding and condition of age-0 walleye pollock (Theragra chalcogramma) in frontal regions of the Bering Sea     

Brodeur  Richard D.; Wilson  Matthew T.; Ciannelli  Lorenzo 《ICES Journal of Marine Science》2000,57(2):256-264

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地球自转速率变化影响大气环流的事实及机制探讨   总被引：1，自引：0，他引：1  

黄玫  彭公炳  沙万英 《地理研究》1999,18(3):254-259

通过相关分析从统计学角度探讨了地球自转速率变化对北半球月平均500HPa大气环流的影响,同时探讨了这一影响的物理机制。  相似文献   

南岭-武夷交汇区的深部背景及地壳泊松比   总被引：1，自引：0，他引：1       下载免费PDF全文

韩如冰  李秋生  徐义贤  张洪双  陈昊  郎超  吴庆宇  王晓冉 《地球物理学报》2019,62(7):2477-2489

为研究南岭-武夷交汇区深部动力学过程提供深部背景资料和科学依据,本文利用远震P波接收函数H-κ叠加和共转换点（CCP）叠加两种方法获取了研究区66个宽频带流动台站及24个固定台站下方的地壳厚度、泊松比和Moho面起伏形态,揭示了扬子地块与华夏地块地壳结构及泊松比变化特征,给出了南岭和武夷之间一条莫霍凸起带的高分辨图像.
结果显示：（1）研究区内地壳厚度平均值为31.2 km,泊松比平均值为0.23,总体呈现薄地壳、低泊松比的特点.地壳厚度从西北往东南由厚变薄,与区域地壳伸展特征相一致.（2）在韶关-赣州-吉安-南昌一线存在条带状薄地壳结构,平均值为28 km,呈南西-北东向展布,对应的泊松比值略微升高.推测地壳减薄带的形成可能与来自南海方向的地幔热流上涌有关.（3）江南造山带的泊松比整体偏低,存在两处平均值小于0.21的区域.华夏地块内地壳厚度与泊松比之间存在弱的负相关,表示随着地壳厚度的增大,铁镁质的下地壳厚度在整个地壳厚度中所占的比例减小.  相似文献   

影响防城港市的热带气旋灾害评估方法     

卢峰本  黄滢  许文龙 《气象研究与应用》2005,26(2):14-15

对1970~2003年影响防城港市的热带气旋造成的灾情进行定量评估研究,应用灾情指数,客观划分灾情等级,用来表示受灾程度,利用逐步回归方法,建立影响防城港市的热带气旋灾情定量评估和预估方法。  相似文献