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Reduced order observer based identification of base isolated buildings

Earthquake Engineering and Engineering Vibration 2003年第2期2卷 237-244页

作者： Satish Nagarajaiah Prasad Dharap Dept.of Civil and Env.Eng. Rice UnivHoustonTX 77005 USA Associate Professor Dept.of Civil and Env.Eng. Rice UnivHoustonTX 77005 USA Graduate Student

The objective of this study is to identify system parameters from the recorded response of base isolated buildings,such as USC hospital building,during the 1994 Northridge *** state measurements are not available for ***,the response is nonlinear due to the yielding of the lead-rubber *** new approaches are presented in this paper to solve the aforementioned ***,a reduced order observer is used to estimate the unmeasured ***,a least squares technique with time segments is developed to identify the piece-wise linear system *** observer is used to estimate the initial conditions needed for the time segmented identification.A series of equivalent linear system parameters are identified in different time *** is shown that the change in system parameters,such as frequencies and damping ratios,due to nonlinear behavior of the lead-rubber bearings,are reliably estimated using the presented *** is shown that the response was reduced due to yielding of the lead-rubber bearings and period lengthening.

关键词： use hospital building base isolation least squares system identification time segments reduced order observer Northridge earthquake

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Application of Kinetic Models in Describing Soil Potassium Release Characteristics and Their Correlations with Potassium Extracted by Chemical Methods

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Pedosphere 2013年第4期23卷 482-492页

作者： A. R. HOSSEINPUR H. R. MOTAGHIAN Department of Soil Science College of Agriculture Shahrekord University

Potassium （K） release characteristics in soil play a significant role in supplying available K. Information on K-release characteristics in soils of central Iran is limited. The objectives of this study were to determine K release characteristics and correlations of K release rate constants with K extracted by different chemical methods in surface soils of ten calcareous soils of central Iran. The kinetics of K release in the soils was determined by successive extraction with 0.01 mol L-1 CaC12 in a period of 2-2017 h at 25±1℃. Soil K was extracted by distilled water, 0.5 mol L-1 MgNO3, 0.002 mol L-1 SrC12, 0.1 mol L-1 BaC12, 0.01 mol L-1 CaC12, 1 mol L-1 NaC1, 1 mol L-1 boiling HNO3, 1 mol L-1 NH4OAC, Mehlich 1, 0.002 mol L-1 SrC12 ＋ 0.05 mol L-1 citric acid, and ammonium bicarbonate-diethylenetriamine pentaacetic acid （AB-DTPA）. A plot of cumulative amounts of K released showed a discontinuity in slope at 168 h. Thus, two equations were applied to two segments of the total reaction time （2-168 and 168-2 017 h）. Cumulative amounts of K released ranged from 55 to 299 mg kg-1 in 2-168 h and from 44 to 119 mg kg-1 in 168-2 017 h. Release kinetics of K in the two time segments conformed fairly well to parabolic diffusion, simplified Elovich, and power function models. There was a wide variation in the K release rate constants. Increasingly higher average concentrations of soil K were extracted by distilled water, Mehlich 1, SrC12, CaC12, SrC12 ＋ citric acid, AB-DTPA, MgNO3, NaCI, NH4OAc, BaCI2, and HNO3. Potassium release rate constants were significantly correlated with K extracted. The results of this study showed that information obtained from mathematical modeling in two reaction time segments can help to estimate the K-supplying power of soils.

关键词： chemical extraction calcareous soils mathematical modeling release rate constant time segments

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