多目标规划在哈尔滨市地下水资源管理中的应用     

王来生  杨天行  徐红敏  宋丽红 《吉林大学学报(地球科学版)》2001,31(2):156-159

建立了哈尔滨市地下水资源优化管理模型 ,将求解多目标最优化问题的约束法和线性加权法相结合 ,给出了一种综合解法 ,并将此法应用于所建立的水资源优化管理模型的求解。其结果可为该地区地下水资源的管理提供有参考价值的科学依据。  相似文献   

Pounding of structures modelled as non‐linear impacts of two oscillators     

K. T. Chau  X. X. Wei 《地震工程与结构动力学》2001,30(5):633-651

A new formulation is proposed to model pounding between two adjacent structures, with natural periods T₁ and T₂ and damping ratios ζ₁ and ζ₂ under harmonic earthquake excitation, as non‐linear Hertzian impact between two single‐degree‐of‐freedom oscillators. For the case of rigid impacts, a special case of our analytical solution has been given by Davis (‘Pounding of buildings modelled by an impact oscillator’ Earthquake Engineering and Structural Dynamics, 1992; 21 :253–274) for an oscillator pounding on a stationary barrier. Our analytical predictions for rigid impacts agree qualitatively with our numerical simulations for non‐rigid impacts. When the difference in natural periods between the two oscillators increases, the impact velocity also increases drastically. The impact velocity spectrum is, however, relatively insensitive to the standoff distance. The maximum relative impact velocity of the coupled system can occur at an excitation period T_n^* which is either between those of the two oscillators or less than both of them, depending on the ratios T₁/T₂ and ζ₁/ζ₂. Although the pounding force between two oscillators has been primarily modelled by the Hertz contact law, parametric studies show that the maximum relative impact velocity is not very sensitive to changes in the contact parameters. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Evaluation of response and energy in actively controlled structures     

Kevin K. F. Wong  Rong Yang 《地震工程与结构动力学》2001,30(10):1495-1510

A computational method of energy evaluation is derived to study the elastic responses and energy distribution of actively controlled single‐degree‐of‐freedom (SDOF) structures during earthquakes. Contrary to the common perception that applying active control force pumps energy into the structure, the applied control force can actually reduce the energy in the structure by reducing the input energy from earthquakes to the structure. In addition, applying control force can dissipate a large amount of energy in the structure when this control force is applied in the direction opposite to the displacement and velocity responses. To demonstrate this energy mechanism in active controlled structures, the two most popular control algorithms, optimal linear control (OLC) and instantaneous optimal control (IOC) algorithms, are used to calculate the control response and energy spectra. One‐step time delay is incorporated into the algorithms to take into consideration the practical aspect of active control. The effects of different earthquakes and damping ratios on control energy and response spectra are studied. These studies show that both OLC and IOC are very effective in reducing the structural displacement and velocity responses by reducing the input earthquake energy as well as dissipating a large amount of energy in the structure. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

Effectiveness of structural control based on control energy perspectives     

Kevin K. F. Wong  Rong Yang 《地震工程与结构动力学》2001,30(12):1747-1768

A computational algorithm for maximizing the control efficiency in actively controlling the elastic structural responses during earthquake is proposed. Study of optimal linear control using a single degree of freedom shows that applying active control is very effective in reducing the structural displacement and velocity responses for long‐period structures, but at the same time it has an adverse effect in increasing the absolute acceleration response. The extent of this adverse effect reduces the effectiveness of the control system, and therefore it poses a limit on the maximum control force in order to provide maximum control efficiency. In view of this shortcoming, maximum control energy dissipation is used to define the most effective optimal linear control law. Less displacement and velocity response are expected as larger control force is applied, but there is always a limit that maximum control energy can be dissipated. This study shows that this limit depends on the structural characteristics as well as the input ground motion, and a general trend is that the maximum control energy decreases as damping increases. Finally, application of the proposed algorithm on a six‐storey hospital building is presented to show the effectiveness of using optimal linear control on a multi‐degree‐of‐freedom system from the control energy perspectives. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   

双线偏振雷达测雨效果的对比分析   总被引：8，自引：2，他引：8  

刘黎平  钱永甫  王致君  楚荣忠 《大气科学》1996,20(5):615-619

本文根据1993、1994年15次层状云和12次对流云降雨过程的地面降雨资料和C波段双线偏振雷达资料，对双线偏振雷达和普通雷达测量不同强度降雨的效果进行了评估和比较。结果表明，从相对误差来看，双线偏振雷达使普通雷达的小雨高估、大雨低估的测量误差趋势减弱，它对小到中雨的测量结果优于普通雷达。双线偏振雷达大雨高估的现象可能与强对流性降雨中冰相粒子的存在有关。  相似文献   

Modifications of the dispersion relations for surface waves in a layer on a half-space     

Oldřich Novotný  L. V. Burlako  T. A. Proskuryakova 《Studia Geophysica et Geodaetica》1996,40(2):167-177

Summary Dispersion relations for Love and Rayleigh waves in a layer on a half-space are modified by introducing quadratic slownesses instead of velocities. The advantages of this approach are demonstrated on analytical formulae for computing the group velocity.  相似文献   

自回归总径流线性响应模型在洪水预报中的应用   总被引：1，自引：0，他引：1       下载免费PDF全文

李蝶娟  周冰清 《水科学进展》1992,3(2):142-148

采用自回归总径流线性响应(ATLR)模型建立淮河王家坝站洪水预报方案和海河流域南运河水系洪水预报调度方案.自回归TLR模型与TLR模型加误差自回归实时校正模型的结构相同,但前者计算简捷,预报精度也有所提高.  相似文献   

Histogram and scattergram smoothing using convex quadratic programming   总被引：1，自引：0，他引：1  

Wenlong Xu  André G. Journel 《Mathematical Geology》1995,27(1):83-103

An algorithm, based on convex quadratic programming, is proposed to smooth sample histograms. The resulting smoothed histogram remains close to the original histogram and honors target mean and variance. The algorithm is extended to smooth sample scattergrams. The resulting smoothed scattergram remains close to the original scattergram shape and the two previously smoothed marginal distributions and honors the target correlation coefficient.  相似文献   

地下水资源系统多目标管理模型与模糊带权二次规划方法   总被引：2，自引：0，他引：2  

谢新民 《水文地质工程地质》1993,20(4):17-21,43

本文以济南地下水资源系统保泉供水管理课题为例,分析研究地下水资源系统多目标管理问题。首先建立起地下水资源系统多目标管理模型;然后利用模糊数学理论和权重概念,提出一种求解多目标决策问题的模糊带权二次规划方法,此方法可以同时解决互为竞争、互为矛盾的各目标之间的不可公度性和主次性问题。实际计算表明,所建立的模型和提出的方法具有较强的实用性和通用性。  相似文献   

重力资料的三维密度反演     

黄卫祖 《吉林大学学报(地球科学版)》1993,(1)

分别论述了在空间域与频率域中由重力资料反演三维密度分布的理论及其实现的方法,并提出了一种简便、实用的频率域三维密度反演算法。  相似文献