筒型基础系缆平台使用过程原型测试分析   总被引：2，自引：0，他引：2  

戎贤  丁红岩  黄金明 《地震工程与工程振动》2003,23(5):134-140

本文介绍在国内首次开展的多筒筒型基础平台在使用过程中的原型测试分析研究。对所采用的测试系统和测试方法作了概要描述，对冰荷载、结构动力响应以及筒型基础反力等同步测量数据进行了初步分析。结果表明，本次采取的测量系统是稳定可靠的，其测量数据是可信的。这项成果的取得为筒型基础平台的计算理论和方法的发展提供了原型结构的印证数据，对筒型基础平台的设计具有直接的参考意义。  相似文献   

卡帕藻的营养成分分析及综合比较     

周歧存  刘东超  叶富良  揭振英  黎祖福 《广东海洋大学学报》2001,21(1):43-46

于1999年元月在海南陵水黎安港采集卡帕藻，应用HPLC、原子吸收等分析手段，系统测定其营养成分（主要包括蛋白质、氨基酸、脂肪、粗纤维、粗灰分、矿物质及微量元素等），并与其它几种大型藻类比较，综合评价卡帕藻的营养价值。结果表明卡帕藻蛋白质含量为6.20%，而粗脂肪和粗灰分较高，分别为2.88%和39.04%；卡帕藻中富含K、Na、Ca、Mg、P、Fe、Zn、Mn、Se等矿物元素，尤其是Se的含量远高于其它几种大型藻类。  相似文献   

现代农业发展中作物养分管理与调控     

翁伯琦  赵雅静  郑祥洲  王义祥  叶菁 《福建地理》2014,(2):10-17

发展现代农业是应对当今世界农业发展面临的粮食安全与资源安全双重挑战的有效方式,同时农业养分管理与调控是现代农业发展的关键课题。现代农业养分管理与调控是一种系统的综合策略,是和谐农业资源与农业生物关系的综合管理策略过程,其目的是使农业的综合生产能力得到提高、系统的稳定性和持续性进一步增强,实现农业的持续增长。本研究针对中国农业生产面临的人多地少的严峻情况、农业土壤养分过量累积而利用率较低的劣势以及农业生产增肥不增产的复杂难题,阐述了现代农业发展中农业养分管理与调控的方向。  相似文献   

中国地壳运动观测网络基准站重力场变化的海潮负荷信号改正问题   总被引：7，自引：0，他引：7  

孙和平  周江存 《地球科学进展》2002,17(1):39-43

利用最新的全球海潮模型（Csr3．0，Fes95．2，Tpxo2和Csr4．0）和原有的Schwiderski海潮模型以及中国近海海潮数据和标准地球模型负荷格林函数，采用直接褶积积分方法研究了中国地壳运动观测网络25个基准站重力固体潮观测中的海潮负荷效应问题，计算了 8个主要潮汐波的负荷振幅和相位，构制了北京和上海等10个台站重力负荷随时间变化函数。  相似文献   

Nutrient enrichment does not affect diet selection by a tropical shredder species in a mesocosm experiment     

《Limnologica》2021

The decomposition of plant litter is a fundamental ecological process in small forest streams. Litter decomposition is mostly controlled by litter characteristics and environmental conditions, with shredders playing a critical role. The aim of this study was to evaluate the effect of leaf species (Maprounea guianensis and Inga laurina, which have contrasting physical and chemical characteristics) and water nutrient enrichment (three levels) on leaf litter chemical characteristics and fungal biomass, and subsequent litter preference and consumption by Phylloicus sp. (a typical shredder in tropical streams). Maprounea guianensis leaves had lower lignin and nitrogen (N) concentrations, higher polyphenols concentration and lower lignin:N ratio than I. laurina leaves. Phosphorus concentrations were higher for both leaf species incubated at the highest water nutrient level. Fungal biomass was higher on M. guianensis than on I. laurina leaves, but it did not differ among nutrient levels. Relative consumption rates were higher when shredders fed on M. guianensis than on I. laurina leaves, due to the lower lignin:N ratio and higher fungal biomass of M. guianensis. Consumption rates on M. guianensis leaves were higher for those exposed to low water nutrient levels than for those exposed to moderate water nutrient levels. Feeding preferences by shredders were not affected by leaf species or nutrient level. The low carbon quality on I. laurina leaves makes it a less attractive substrate for microbial decomposers and a less palatable resource for shredders. Changes in litter input characteristics may be more important than short-term nutrient enrichment of stream water on shredder performance and ecosystem functioning.  相似文献   

Prediction and validation of sidesway collapse of two scale models of a 4‐story steel moment frame     

D. G. Lignos  H. Krawinkler  A. S. Whittaker 《地震工程与结构动力学》2011,40(7):807-825

A research program is summarized in which collapse of a steel frame structure is predicted numerically and the accuracy of prediction is validated experimentally through earthquake simulator tests of two 1:8 scale models of a 4‐story code‐compliant prototype moment‐resisting frame. We demonstrate that (1) sidesway collapse can occur for realistic combinations of structural framing and earthquake ground motion; (2) P?Δeffects and component deterioration dominate behavior of the frame near collapse; (3) prediction of collapse is feasible using relatively simple analytical models provided that component deterioration is adequately represented in the analytical model; and (4) response of the framing system near collapse is sensitive to the history that every important component of the frames experiences, implying that symmetric cyclic loading histories that are routinely used to test components provide insufficient information for modeling deterioration near collapse. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Seismic response evaluation of an urban overpass     

Juan M. Mayoral  Francisco A. Flores  Miguel P. Romo 《地震工程与结构动力学》2011,40(8):827-845

The seismic response of one section of a 23 km strategic urban overpass to be built in the so‐called transition and hill zones in Mexico City is presented. The subsoil conditions at these zones typically consist on soft to stiff clay and medium to dense sand deposits, randomly interbedded by loose sand lenses, and underlain by rock formations that may outcrop in some areas. Several critical supports of this overpass are going to be instrumented with accelerometers, inclinometers and extensometers, tell tales and end pile cell pressures to assess their seismic performance during future earthquakes and to generate a database to calibrate soil–structure interaction numerical models. This paper presents the seismic performance evaluation of the critical supports located in one section of the overpass. Sets of finite elements models of the soil–foundation–structure systems were developed. Initially, the model was calibrated analyzing the seismic response that an instrumented bridge support exhibited during the June 15th, 1999 Tehuacan (M_w = 7) Earthquake. This bridge is located also within the surroundings of Mexico City, but in the lake zone, where highly compressible clays are found. The computed response was compared with the measured response in the free field, pile‐box foundation and bridge deck. Once the model prediction capabilities were established, the seismic response of the critical supports of the urban overpass was evaluated for the design earthquake in terms of transfer functions and displacement time histories. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

地铁荷载下粉性土动力特性研究进展          下载免费PDF全文

闫春岭  唐益群 《地震工程学报》2011,33(2):200-205

近年来中国各大城市为解决城市交通问题而大力兴建地铁工程,由此引发的工程环境问题也越发明显.本文对国内外地铁荷载作用下土体的动力响应理论、地铁荷载下粉性土动力特性试验以及地铁隧道长期沉陷等研究进行评述,分析和总结了地铁循环荷载作用下粉性土研究中存在的问题,并提出了今后研究的发展趋势.  相似文献   

非饱和黄土震陷物理力学机制与主导影响因素   总被引：1，自引：0，他引：1  

孙军杰  王强  王兰民 《地震工程学报》2011,33(Z1)

通过分析黄土震陷的物理过程及其力学机制,指出非饱和黄土震陷实质上是土体广义固相介质响应外部动荷载作用的再固结过程。将影响黄土震陷的主导因素归纳为两方面,即土体广义固相介质的强度、体积特征和外部动荷载特征。介质的强度特征可通过引入土工试验获取的参数(粘聚力和内摩擦角)来宏观表征;体积特征可由能够反映土体欠压密程度的孔隙比描述。与非饱和黄土震陷的宏观物理力学机制相适应,粘聚力与内摩擦角主要反映土体的结构性强度(黄土强度特征),孔隙比则反映了土体再固结的潜在性态(黄土沉降量值特征);黄土强度特征对应土体抵御外部载荷的能力,黄土沉降量值特征对应外部载荷作用下的土体沉降能力。  相似文献   

减震装置提高防护门抗力的理论分析     

宋春明  王明洋  刘斌 《地震学刊》2011,(6):700-703,709

在端部采用减震装置可提高防护门的抗力,而且该减震装置会影响防护门的振动特性和动力响应,因此对其在爆炸载荷作用下的动态响应分析非常重要。本文建立了具有减震装置防护门的计算模型,推导出了结构在爆炸荷载作用下的解析计算式,分析了化爆和核爆荷载作用下减震装置对振动的影响规律。结果表明,由弹性支承和阻尼器组成的减震装置可以明显降低结构的动力系数,从而提高防护门的抗力,但提高的效果与弹性支承的刚度、载荷作用时间的长短以及振动衰减的程度相关。  相似文献