粘滞阻尼器消能减震结构的简化设计

基于pushover分析方法，提出粘滞阻尼器消能减震结构的一个简化设计方法．先将多自由度体系等价成单自由度体系，对于给定的目标顶点位移，可以直接求出等价单自由度体系抵御强震所需的等价附加阻尼，并对其在多自由度体系中的分配提出建议．选用一个12层混凝土框架结构验证了该方法，其时程分析结果表明，对于pushover方法适应范围内的中、低层房屋可以取得满意的结果．     

剪力墙结构在地震作用下的非线性分析

本文运用非协调单元和动态子结构技术，使地震作用下的钢筋混凝土剪力墙结构非线性有限元分析在微机上得以实现，比常用的层间模型和杆系模型更精确地描述了剪力墙从开裂到破坏的全过程，对清华大学所做两个开洞剪力墙结构模型的振动台试验作了全过程模拟，计算结构与试验结果吻合良好。     

粘性Cahn-Hilliard方程的高精度线性化差分方法

讨论粘性Cahn-Hilliard方程的高精度线性化差分方法.利用降阶法对粘性Cahn-Hilliard方程建立三层线性化紧差分格式.用离散能量分析法证明差分格式的唯一可解性及在L_∞-范数下的收敛性,其收敛阶为时间方向二阶、空间方向四阶.最后,通过数值算例验证了差分格式的理论结果.     

二元立木材积模型的联立方程组估计方法

文章以兴安落叶松为例,使用联立方程组模型方法建立二元立木材积模型,该方法有效解决了二元立木材积模型的建模和预估前提不一致问题。在联立二元立木材积模型的估计中,分别采用了通常非线性估计方法和两步估计方法进行研究。研究结果证明:两种方法都能对模型进行估计,但两步估计可进一步减小系统偏差,达到通用性模型误差限要求,两步估计方法优于通常非线性估计。     

Aging Behavior Analysis of Asphalt based on Nonlinear Differential Dynamic Model

In order to study aging behavior and anti aging performance of asphalt, aging tests were carried out with rolling thin film oven test(RTFOT) and oven aging test at 60℃, and aged asphalt was extracted from pavements of different service life. Viscosity of asphalt samples was fitted with nonlinear differential dynamic model. With parameter study, property changes, aging rate of asphalt and the difference of aging mechanism were analysed under different aging conditions. It was shown that the nonlinear differential dynamic model can simulate asphalt aging process in the laboratory or on site effectively. At the same time, model parameters(L and r) can quantify aging state and aging rate. Asphalt had its limited aging state corresponding with different aging temperature. Ultimate aging degree of RTFOT and field aging were about 4~5 times of that of oven aging test at 60 ℃. And aging effect of RTFOT for 6h was about equivalent with that of field aging for 6 years. Thus time delay RTFOT can simulate long term aging of pavement asphalt.     

Practical Method of Form-finding of Semi-rigid Structures

Based on the discussion of the simulation for the cable prestress, the rigidity theory was used to identify the geometrical dimensions of semi-rigid structures in zero state. When the structural geometry in initial state is given, the geometrical dimension in zero state is determined by the initial prestress distribution. The contribution-matrix method is firstly applied to get the initial lack of fit. However, the influencing factor of initial lack of fit on the displacement of control point is linear superposition, that is, the structural response is linear, and it is irreconcilable with the geometry nonlinear of semi-rigid structure. In order to reduce the error of nonlinear structural response, the influencing factor in the contribution-matrix method is revised, and modified contribution-matrix method is put forward. Programs by ANSYS parameter design language APDL are worked out for the form-finding analysis of beam-string structure of a practical project. The numerical results show that the modified contribution-matrix method reduces the errors of the assumption of structural linear response. And it can be applied to the form-finding of semi-rigid structures with small stiffness.     

Soil water-retention prediction from pedotransfer functions for some Indian soils

This paper discusses the development of pedotransfer functions (PTFs) and uses a multiple nonlinear regression technique to validate point and parametric PTFs for the estimation of a water-retention curve from basic soil properties such as particle-size distribution, bulk density and organic matter content. One hundred soil samples were collected at different depths from different locations in the Pavanje river basin that lies within the southern coastal region of Karnataka, India. Prediction accuracies were evaluated using the coefficient of determination (R ²), root mean square error (RMSE) and mean error (ME) between measured and predicted values. Overall, both point and parametric methods predicted water contents at selected water potentials with considerable accuracy. However, prediction of the soil water-retention curve using PTFs by point estimation method was relatively more successful (best case R ² = 0.983) for the sampled soils. F-tests were also conducted for all cases. For one regression equation, the p-value was zero and for other equation, values were close to zero. Critical comparative analysis was carried out on the performances of the point and parametric methods. Use of the developed PTFs is suggested for the prediction of a water-retention curve for loamy sand and sandy loam soils in this area of the coastal region of southern India.     

基于流函数理论的近海风机非线性波浪荷载计算

《宋史·礼志》的史料价值主要体现在四个方面：一是记载较为系统与丰富,包括总体和局部两种情况;二是保存了部分珍贵史料,如诏令奏议、礼论等;三是订正他书讹误与不足,有时间误、人名误、职官误、地点误等;四是后世官私著述之史源。     

一类高阶非线性泛函微分方程的强迫振动性

给出了一类非线性泛函微分方程的新的强迫振动条件,推广了文献中的一些结果,同时还给出了一类非线性强迫中立型方程的振动条件．     

GPS网平差的多元响应模型及参数估计

本文针对CPS测量数据为多元响应数据的特点,建立了一个CPS网平差的多元响应模型,讨论了模型的性质,在几种情形下,给出了参数的极大似然估计与非线性最小二乘估计的非线性优化模型,讨论了参数估计的求解方法。