共查询到20条相似文献，搜索用时 265 毫秒
1.
A novel hybrid methodology is introduced in this paper for the optimal solution of the groundwater management problem. The problem to be addressed is the optimal determination and operation of a predefined number of wells out of a priori known set of potential wells with fixed locations to minimize the pumping cost of utilizing a two‐dimensional (2D) confined aquifer under steady‐state flow condition. The solution to this problem should satisfy a downstream demand, a lower/upper bound on the pumping rates, and a lower/upper bound on the water level drawdown in the wells. The problem is solved by hybridizing a genetic algorithm (GA) which suggests the candidate configurations for the operational wells and a hybrid linear programming (LP‐LP) approach with the duty of finding the optimal operation policy of the candidate wells defined by their pumping rates. Two different codings, namely binary and integer codings, are used for the GA and their performances are compared. The ability of the proposed hybrid method is tested against two benchmark problems: (1) finding the optimal configuration and pumping rates of a predefined number of wells out of potential wells and (2) finding the optimal number, configuration and pumping rates of the operating wells out of potential wells and the results are presented and compared with the available ones showing superior efficiency and effectiveness of the proposed method. 相似文献
2.
A mathematical formulation for optimal control of air pollution 总被引：3，自引：0，他引：3
In recent years the urban air pollutions caused by emissions from industry, transportation and energy consuming for daily living are getting worse in many major cities of China. Peoples awareness on air quality is increasing. Routine monitoring and foreca… 相似文献
3.
The problem of variational data assimilation for a nonlinear evolution model is formulated as an optimal control problem to
find the initial condition function. The equation for the error of the optimal solution (analysis) is derived through the
errors of the input data (background and observation errors). The numerical algorithm is developed to compute the sensitivity
coefficients for the analysis error using the fundamental control functions. Application to the variational data assimilation
problem for a model of ocean thermodynamics is considered. 相似文献
4.
Considerable effort has been devoted to develop optimal control methods for reducing structural response under seismic forces. In this study analytical solution of the linear regulator problem applied widely to the control of earthquake‐excited structures is obtained by using the sufficient conditions of optimality even though almost all of the optimal controls proposed previously for structural control are based on the necessary conditions of optimality. Since the resulting optimal closed–open‐loop control cannot be implemented for civil structures exposed to earthquake forces, the solution of the optimal closed–open‐loop control is carried out approximately based on the prediction of the seismic acceleration values in the near future. Upon obtaining the relation between the exact optimal solution and future values of seismic accelerations, it is shown numerically that the solution of the optimal closed–open‐loop control problem can be performed approximately by using only the first few predicted seismic acceleration values if a given norm criteria is satisfied. Calculated performance measures indicate that the suggested approximate solution is better than the closed‐loop control and as we predict the future values of the excitation more accurately, it will approach the optimal solution. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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This paper presents a chance-constrained programming model for optimal control of a multipurpose reservoir and its modification to a model for single reservoir design. An algorithm is developed for solving complex stochastic problems of multipurpose reservoir planning and design. The complexity of the problem is resolved by a two-step algorithm: (1) transformation of chance constraints on the state and control variables is performed at the first step; and (2) the choice of optimum control or optimal reservoir storage is carried out in the second step. The method of iterative convolution is chosen for the first step, while linear programming is selected for the second step. The algorithm allows the use of random inflows and random demands together with other deterministic demands. The reservoir design problem is presented as a modified optimal control problem. The procedure is illustrated with an example of a hypothetical reservoir design problem with three different types of downstream releases (hydropower production, municipal water supply, and irrigation). 相似文献
7.
Yoshihiro Kanno 《地震工程与结构动力学》2013,42(11):1657-1676
Supplemental damping is known as an efficient and practical means to improve seismic response of building structures. Presented in this paper is a mixed‐integer programming approach to find the optimal placement of supplemental dampers in a given shear building model. The damping coefficients of dampers are treated as discrete design variables. It is shown that a minimization problem of the sum of the transfer function amplitudes of the interstory drifts can be formulated as a mixed‐integer second‐order cone programming problem. The global optimal solution of the optimization problem is then found by using a solver based on a branch‐and‐cut algorithm. Two numerical examples in literature are solved with discrete design variables. In one of these examples, the proposed method finds a better solution than an existing method in literature developed for the continuous optimal damper placement problem. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
8.
Earthquake prediction as a decision-making problem 总被引：11，自引：0，他引：11
G. M. Molchan 《Pure and Applied Geophysics》1997,149(1):233-247
In this review we consider an interdisciplinary problem of earthquake prediction involving economics. This joint research aids in understanding the prediction problem as a whole and reveals additional requirements for seismostatistics. We formulate the problem as an optimal control problem: Prossessing the possibility to declare several types of alerts, it is necessary to find an optimal changing alert types; each successful prediction prevents a certain amount of losses; total expected losses are integrated over the semi-infinite time interval. The discount factor is included in the model. Algorithmic and exact solutions are indicated.This paper is based on the recent results byMolchan (1990, 1991, 1992). 相似文献
9.
A general method is developed for optimal application of dampers and actuators by installing them at optimal location on seismic-resistant
structures. The study includes development of a statistical criterion, formulation of a general optimization problem and establishment
of a solution procedure. Numerical analysis of the seismic response in time-history of controlled structures is used to verify
the proposed method for optimal device application and to demonstrate the effectiveness of seismic response control with optimal
device location. This study shows that the proposed method for the optimal device application is simple and general, and that
the optimally applied dampers and actuators are very efficient for seismic response reduction. 相似文献
10.
本文建立了基于二次型性能指标的结构控制系统控制器最优布置方法。以控制器撤除时的系统最优控制性能指标增量作为控制器对系统最优控制的贡献，并用做确定经济的控制器数量和最优控制器位置的定量分析准则。本文中的控制器位置和控制器设计采用同一个优化性能指标，使得控制系统设计为最优。根据逼近满设置控制器结构控制系统的最优状态求得控制器降阶后等价的反馈控制增益。应用本文的方法对剪切模型框架结构上安装的锚索控制器进行了控制器的总体优化设计。数值分析表明，本文提出的控制器数量、位置和参数优化方法不仅易于实现，而且甚为有效。 相似文献
11.
Verifying optimality of rainfed agriculture using a stochastic model for drought occurrence 总被引：1，自引：1，他引：0
Erfaneh Sharifi Koichi Unami Macarius Yangyuoru Masayuki Fujihara 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(5):1503-1514
It may be paradoxical but subsistence rainfed agriculture is the predominant source of food in Sub-Saharan Africa where the production uncertainty is associated with the stochastic nature of rainfall. This paper attempts to comprehend the rationale of this situation by a mathematical approach. Considering the level of drought severity as the zero-reverting Ornstein–Uhlenbeck process, optimality of rainfed agriculture is investigated in the context of stochastic control theory. Occurrence of drought terminating growth of crops is modelled with the concept of first exit time. A stochastic control problem allowing for virtual cost of irrigation, water stress to crops, and benefits of farming is formulated with irrigation effort as the control variable. The Hamilton–Jacobi–Bellman equation governing the optimal control is studied to identify the set of cost functions optimizing rainfed agriculture in an inverse problem approach. Data and information were collected in the coastal savanna agro-ecological zone of Ghana, to identify model parameters, formulate the stochastic control problem, solve the inverse problem, and then verify optimality of rainfed agriculture. The results indicated that rainfed agriculture is not optimal when the crop is more tolerant to water stress. 相似文献
12.
A new class of algorithms for solving the inverse problems of gravity prospecting is considered. The best interpretation is selected from the set Q of the admissible versions by the optimality criteria that are borrowed from the solution-making theory and adapted for the geophysical problems. The concept of retrieving the information about the sources of gravity anomalies, which treats the result of the interpretation as a set of locally optimal solutions of the inverse problem but not as a single globally optimal solution is discussed. The locally optimal solutions of the inverse problem are sort of singularity points of set Q. They are preferable to the other admissible solutions by a certain criterion formulated in terms of the geologically important information about the anomalous bodies. The admissible versions of the interpretation of the gravimetry data that meet the criteria of the decision-making theory are the primary candidates for the singularity points. The results of the numerical calculations are presented. The set of the admissible solutions from which the locally optimal versions of interpretation are selected is formed by the modifications of the assembly method developed by V.N. Strakhov. 相似文献
13.
《Advances in water resources》1996,19(4):215-224
In groundwater modeling the identification of an optimal flow or transport parameter that varies spatially should include both the values and structure of the parameter. However, most existing techniques for parameter identification only consider the parameter values. In this study, the problem of identifying optimal parameter structure is treated as a large combinatorial optimization problem. Two recently developed heuristic search techniques, simulated annealing and tabu search, are used to solve the large combinatorial optimization problem. The effectiveness and flexibility of these two techniques are evaluated and compared with simple grid search and descent search, using preliminary results from one-dimensional examples. Among the techniques examined in this paper, tabu search performs extremely well in terms of the total number of function evaluations required. 相似文献
14.
本文把桁架结构地震可靠性分析和最优化设计方法结合起来，以结构的地震失效率概率为目标函数，给出一种考虑地震可靠性的桁架结构的优化方法。该方法能够解决线性桁架体系在平稳的随机地震地面运动激励下的优化问题，并在给定投资的条件下设计出了安全可靠的桁架结构。 相似文献
15.
Monitoring and estimation of snow depth in alpine catchments is needed for a proper assessment of management alternatives for water supply in these water resources systems. The distribution of snowpack thickness is usually approached by using field data that come from snow samples collected at a given number of locations that constitute the monitoring network. Optimal design of this network is required to obtain the best possible estimates. Assuming that there is an existing monitoring network, its optimization may imply the selection of an optimal network as a subset of the existing one (if there are no funds to maintain them) or enlarging the existing network by one or more stations (optimal augmentation problem). We propose an optimization procedure that minimizes the total variance in the estimate of snowpack thickness. The novelty of this work is to treat, for the first time, the problem of snow observation network optimization for an entire mountain range rather than for small catchments as done in the previous studies. Taking into account the reduced data available, which is a common problem in many mountain ranges, the importance of a proper design of these observation networks is even larger. Snowpack thickness is estimated by combining regression models to approach the effect of the explanatory variables and kriging techniques to consider the influence of the stakes location. We solve the optimization problems under different hypotheses, studying the impacts of augmentation and reduction, both, one by one and in pairs. We also analyse the sensitivity of results to nonsnow measurements deduced from satellite information. Finally, we design a new optimal network by combining the reduction and augmentation methods. The methodology has been applied to the Sierra Nevada mountain range (southern Spain), where very limited resources are employed to monitor snowfall and where an optimal snow network design could prove critical. An optimal snow observation network is defined by relocating some observation points. It would reduce the estimation variance by around 600 cm2 (15%). 相似文献
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The optimal sequencing of a multipurpose water supply system in the Hajduhátság region of Hungary is determined by dynamic programming. The goal function minimizes the present value of capital costs, operation costs, and economic losses due to water shortages. Future water requirements are considered to be random variables because of natural and forecasting uncertainties. The nonlinear optimization problem at each stage is equivalent to a readily solved game theoretical problem, the solution of which is straightforward. Sensitivity analysis performed with respect to economic losses, water requirements and discount rate, showed that optimal development and sequencing depend largely on the economic losses and the discount rate. 相似文献
18.
《Advances in water resources》1998,21(7):591-604
A heuristic algorithm is presented for problems which are formulated to find an optimal groundwater remediation strategy with constraints on confined groundwater flow and contaminant transport. The problem is simplified by decoupling the transport constraints from the hydraulic constraints to produce a linear hydraulic control optimization problem. The solution is obtained by an iterative process in which the constraints on hydraulic gradient are updated, using information from transport simulation, and the hydraulic control problem is solved repeatedly. In effect, the transport simulation is used to calibrate the head difference constraint values of the hydraulic control problem. The algorithm is described in detail and its convergence is demonstrated on several examples. The advantages and limitations of the algorithm are discussed. 相似文献
19.
A model of bacterial culture, utilizing a toxic substrate in continuous flow conditions' is discussed in the present paper. The relative velocity of microorganisms growth is expressed by means of a formula proposed by us, grounded on the analogy of a model of an irreversibly inhibited enzymatic reaction. It is assumed that the integral parameter characterizing the damage of the bacterial cell by a toxic agent may be considered a slow variable in regard to the variation of the biomass and substrate concentrations. An equation for the evolution of this parameter is proposed. A problem of minimum time adaptation of the bacterial population is proposed as a time optimal control problem that is solved on the basis of the Pontryagin maximum principle. This model provides a possibility of studying some regularities in the adaptation mechanism of the microorganisms destroying toxic substances. The same model can also be used to forecast the optimal regimes in cultivation of bacterial cultures that play an essential role in the biological self-purification of various water pools. 相似文献
20.
D. Zidarov 《Pure and Applied Geophysics》1973,110(1):1918-1926
Summary Instead of solving the potential field inverse problem by means of optimal point masses a set of point masses is considered to represent one of the most concentrated (pressed) bodies of the family. This body is divided into layers, each of them represented by some quantity of point masses. 相似文献