摩擦与粘性流体耗能器串联体系动力分析     

吕西林  周强 《地震工程与工程振动》2001,21(1):123-130

采用粘性屈服模型来模拟摩擦耗能器的力－速度关系，建立了摩擦与粘性流体耗能器串联耗能体系的动力分析方法．为考虑框架杆件和支撑材料的几何非线性，采用增量型Ｒｏｓｅｎｂｒｏｃｋ二级三阶半隐式Ｒｕｎｇｅ－Ｋｕｔｔａ法求解动力方程．比较了仅有摩擦耗能器体系与串联组合耗能体系的减振效果，分析了粘性流体耗能器参数对组合耗能体系减振效果的影响。  相似文献   

摩擦耗能框架体系动力分析   总被引：4，自引：0，他引：4  

周强  吕西林 《地震工程与工程振动》2001,21(2):136-144

采用粘性屈服模型来模拟摩擦耗能器的力－速度关系。建立了带有摩擦耗能器体系的动力分析8方法，采用增量型Rosenbrock二阶三阶半隐式Runge-Kutta法求解动力方程，得到了带有摩擦耗能器单层框架在正弦波激励下反应的解析解，并据此验证粘性屈服模型及求解动力方程算法的正确性，分析了摩擦耗能器的起滑力和支撑刚度对耗能减振效果的影响。  相似文献   

The level of deterrence provided by data from the SPITS seismometer array to possible violations of the Comprehensive Test Ban in the Novaya Zemlya region   总被引：1，自引：0，他引：1  

David Bowers  Peter D. Marshall  Alan Douglas 《Geophysical Journal International》2001,146(2):425-438

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Material component to non-linear relation between sediment yield and drainage network development: an flume experimental study     

JIN De-sheng  CHEN Hao  GUO Qing-wu 《地理学报》2001,11(3):271-281

This paper examines the experimental study on influence of material component to nonlinear relation between sediment yield and drainage network development completed in the Lab. The area of flume drainage system is 81.2 m2, the longitudinal gradient and cross section slope are from 0.0348 to 0.0775 and from 0.0115 to 0.038, respectively. Different model materials with a medium diameter of 0.021 mm, 0.076 mm and 0.066 mm cover three experiments each. An artificial rainfall equipment is a sprinkler-system composed of 7 downward nozzles, distributed by hexagon type and a given rainfall intensity is 35.56 mm/hr.cm2. Three experiments are designed by process-response principle at the beginning the Ψ shaped small network is dug in the flume. Running time spans are 720 m, 1440 minutes and 540 minutes for Runs I, IV and VI, respectively. Three experiments show that the sediment yield processes are characterized by delaying with a vibration. During network development the energy of a drainage system is dissipated by two ways, of which one is increasing the number of channels (rill and gully), and the other one is enlarging the channel length. The fractal dimension of a drainage network is exactly an index of energy dissipation of a drainage morphological system. Change of this index with time is an unsymmetrical concave curve. Comparison of three experiments explains that the vibration and the delaying ratio of sediment yield processes increase with material coarsening, while the number of channel decreases. The length of channel enlarges with material fining. There exists non-linear relationship between fractal dimension and sediment yield with an unsymmetrical hyperbolic curve. The absolute value of delaying ratio of the curve  相似文献   

新疆棉花的比较优势:基于粮棉单产比的分析   总被引：3，自引：1，他引：3  

盛承发  苏建伟  王红托  宣维健 《干旱区地理》2001,24(2):109-112

1992～ 1998年新疆、山东、安徽及全国的粮棉单产比分别为 3.75、7.2 4、6 .35、和 5 .0 7,新疆比山东和安徽分别低 3.5和 2 .6。回归分析表明 ,粮棉单产比每下降 1,来年棉产上升 7.8%。综合考虑农民人均收入、棉花运输成本及WTO等因素 ,在皮棉产量达到 175× 10 4 t之前 ,新疆棉花的比较优势不大可能出现大的逆转  相似文献   

A note on the useable dynamic range of accelerographs recording translation   总被引：2，自引：0，他引：2  

M. D. Trifunac  M. I. Todorovska 《Soil Dynamics and Earthquake Engineering》2001,21(4)

Since the late 1970s, the dynamic range and resolution of strong motion digital recorders have leaped from 65 to 135 dB, opening new possibilities for advanced data processing and interpretation. One of these new possibilities is the calculation of permanent displacement of the ground or of structures, associated with faulting or with non-linear response. Proposals on how permanent displacements could be recovered from recorded strong motion have been published since 1976. The analysis in this paper concludes that permanent displacements of the ground and of structures in the near-field can be calculated provided all six components of strong motion (three translations and three rotations) have been recorded, and the records are corrected for transducer rotation, misalignment and cross-axis sensitivity.  相似文献   

农业生态的化学元素分类及其与作物优质高产的关系   总被引：12，自引：0，他引：12  

曾昭华 《湖南地质》2001,20(4):277-283

利用国家科学技术成果，并根据国内外研究现状，将103个化学元素分成对作物生长发育、增产起显著作用、起一定作用、起有害作用和起未知作用4个农业生态元素类型，进而论述了它们与作物优质高产的关系。  相似文献   

广东近40年来5～9用气候变化及与主要农作物关系     

刘黎明  陈创买 《热带地理》1996,(2)

本文以广东省４７个测站近４０年来６～９月降水量、平均气温、总日照时数和一些主要农作物逐年单产量资料为基础，用主分量分析、周期回归等方法，分析广东全省性的气候时空变化特征；分析一些主要农作物逐年单产的变化规律．用多元逐步回归分析方法探讨了广东全省性气候变化与同期及后期（１～３年）主要农作物单产量间的关系并作了预报．  相似文献   

GPS网可靠性强度分析     

吴素芹 《武汉大学学报(信息科学版)》1992,(3)

本文对GPS基线向量网的可靠性进行了探讨,提出了作为相关观测值的单个基线向量的可靠性指标和粗差检验方法,并通过对实测网和模拟网的计算与分析,得出了一些有关GPS基线向量网可靠性设计的建议和结论。  相似文献   

南极中山站附近麦氏贼鸥食性研究          下载免费PDF全文

王自磐 《极地研究》1992,4(1):1-16

对东南极中山站附近麦氏贼鸥巢区和无巢贼鸥群栖地的贼鸥回吐渣团及其他食物残物进行收集、分析和鉴定 ,结果表明 ,本区麦氏贼鸥主要捕食雪　 ,其残物在食物项中的平均出现率为 6 7～ 80 %;同时贼鸥从本区几个考察站觅取人类遗弃的垃圾食物作为其重要的食物补充 ,垃圾食物的平均出现率为 6 .8～ 1 1 .6 %。不同巢区贼鸥对雪　的捕杀量和垃圾的需求差异较大 ,其主要与营巢地域的雪　分布密度以及摄食区的占有与否有关。  相似文献