Multi-objective optimization of cascade reservoirs using NSGA-II: A case study of the Three Gorges-Gezhouba cascade reservoirs in the middle Yangtze River, China

2017 ◽  
Vol 23 (4) ◽  
pp. 814-835 ◽  
Author(s):  
Lingquan Dai ◽  
Peipei Zhang ◽  
Yu Wang ◽  
Dingguo Jiang ◽  
Huichao Dai ◽  
...  
Keyword(s):  
Yangtze River ◽  
Three Gorges ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Cascade Reservoirs ◽  
Multi Objective ◽  
The Three Gorges

Parameter Based Multi-Objective Optimization of Video CODECs

2011 ◽  
pp. 288-308
Author(s):  
F. Al-Abri ◽  
E.A. Edirisinghe ◽  
C. Grecos
Keyword(s):  
Genetic Algorithm ◽  
Mathematical Formulation ◽  
Video Codec ◽  
Video Content ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Video Codecs ◽  
Multi Objective ◽  
On Demand

This chapter presents a generalised framework for multi-objective optimisation of video CODECs for use in off-line, on-demand applications. In particular, an optimization scheme is proposed to determine the optimum coding parameters for a H.264 AVC video codec in a memory and bandwidth constrained environment, which minimises codec complexity and video distortion. The encoding/decoding parameters that have a significant impact on the performance of the codec are initially obtained through experimental analysis. A mathematical formulation by means of regression is subsequently used to associate these parameters with the relevant objectives and define a Multi-Objective Optimization (MOO) problem. Solutions to the optimization problem are reached through a Non-dominated Sorting Genetic Algorithm (NSGA-II). It is shown that the proposed framework is flexible on the number of objectives that can jointly be optimized. Furthermore, any of the objectives can be included as constraints depending on the requirements of the services to be supported. Practical use of the proposed framework is described using a case study that involves video content transmission to a mobile hand.

Multi-Objective Optimization of Manufacturing Processes Using Evolutionary Algorithms

2012 ◽  
pp. 44-66
Author(s):  
M. Kanthababu
Keyword(s):  
Genetic Algorithm ◽  
Evolutionary Algorithms ◽  
Multiple Objectives ◽  
Manufacturing Processes ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Local Optima ◽  
Multi Objective ◽  
Research Areas

Recently evolutionary algorithms have created more interest among researchers and manufacturing engineers for solving multiple-objective problems. The objective of this chapter is to give readers a comprehensive understanding and also to give a better insight into the applications of solving multi-objective problems using evolutionary algorithms for manufacturing processes. The most important feature of evolutionary algorithms is that it can successfully find globally optimal solutions without getting restricted to local optima. This chapter introduces the reader with the basic concepts of single-objective optimization, multi-objective optimization, as well as evolutionary algorithms, and also gives an overview of its salient features. Some of the evolutionary algorithms widely used by researchers for solving multiple objectives have been presented and compared. Among the evolutionary algorithms, the Non-dominated Sorting Genetic Algorithm (NSGA) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) have emerged as most efficient algorithms for solving multi-objective problems in manufacturing processes. The NSGA method applied to a complex manufacturing process, namely plateau honing process, considering multiple objectives, has been detailed with a case study. The chapter concludes by suggesting implementation of evolutionary algorithms in different research areas which hold promise for future applications.

scholarly journals Incorporating ecological adaptation in a multi-objective optimization for the Three Gorges Reservoir

2015 ◽  
Vol 18 (3) ◽  
pp. 564-578 ◽  
Author(s):  
Fang-Fang Li ◽  
Jun Qiu
Keyword(s):  
Optimization Model ◽  
Three Gorges Reservoir ◽  
Flood Control ◽  
Three Gorges ◽  
River Ecosystem ◽  
Multi Objective Optimization ◽  
The Three Gorges Reservoir ◽  
Multi Objective ◽  
The Three Gorges ◽  
Ecological Flow

Evidence from ecological studies has suggested that alteration of river flows downstream of reservoirs can threaten native aquatic ecosystems. The Three Gorges Reservoir has been controversial since its design and construction stage, and the ecological damage downstream is an important concern. However, protecting long-term health of the river ecosystem has a low priority in reservoir operation compared to other human demands, and is traditionally treated as a constraint of minimum water release. A multi-objective reservoir optimization model incorporating ecological adaption is proposed. Range of variability approach is first used to quantify the hydrological alteration. A satisfying ecological flow scenario is then worked out if it is necessary to take ecological issues into consideration. With the aim of eco-compensation, the reservoir release should be as close to satisfying ecological flow as possible, which is set to be the objective for ecological adaption. Together with other objectives, such as flood control and power generation, a multi-objective optimization model is established, which is optimized by NSGA-II algorithm. Results not only provide the operational references in both wet and dry years, but also illustrate the negative impacts on the river ecosystem by reservoirs can be alleviated with low economic cost. Quantitative relationships among different objectives can also be used for trading markets.

scholarly journals Efficient multi-objective optimization methods for computationally intensive urban water resources models

2014 ◽  
Vol 17 (1) ◽  
pp. 36-55 ◽  
Author(s):  
Mohammad Mortazavi-Naeini ◽  
George Kuczera ◽  
Lijie Cui
Keyword(s):  
Ant Colony Optimization ◽  
Water Resource ◽  
Optimization Methods ◽  
Optimization Method ◽  
Ant Colony ◽  
Urban Water ◽  
Multi Objective Optimization ◽  
Nsga Ii ◽  
Multi Objective

Multi-objective optimization methods require many thousands of objective function evaluations. For urban water resource problems such evaluations can be computationally very expensive. The question as to which optimization method is the best choice for a given function evaluations budget in urban water resource problems remains unexplored. The main objective of this paper is to address this question. The second objective is to develop a new optimization algorithm, efficient multi-objective ant colony optimization-I (EMOACO-I), which exploits the good performance of ant colony optimization enhanced using ideas borrowed from evolutionary optimization. Its performance was compared against three established methods (NSGA-II, SMPSO, εMOEA) using two case studies based on the urban water resource systems serving two major Australian cities. The case study problems involved two or three objectives and 10 or 13 decision variables affecting infrastructure investment and system operation. The results show that NSGA-II was the worst performing method. However, none of the remaining methods was unambiguously superior. For example, while EMOACO-I converged more rapidly, its diversity was comparable but not superior to the other methods. Greater differences in performance were found as the number of objectives and case study complexity increased. This suggests that pooling the results from a number of methods could help guard against the vagaries in performance of individual methods.

Multi-objective optimization of the Three Gorges cascaded reservoirs operation with emphasis on electricity generation and ecological requirements

2015 ◽  
Vol 15 (4) ◽  
pp. 753-765 ◽  
Author(s):  
Yue Zhao ◽  
Huan Ying ◽  
Jianzhong Zhou
Keyword(s):  
Power Generation ◽  
Water Resource Management ◽  
Water Volume ◽  
Three Gorges ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Ecological Requirements ◽  
The Three Gorges ◽  
Ecological Flow ◽  
Cascaded Reservoirs

The operations of reservoirs produce enormous economic and social benefits but also impact species composition and habitat distribution of the riverine ecosystem. Hence, the realization of conservation and restoration of the ecosystem calls for reservoir reoperation. It is a widespread consensus that providing suitable ecological flow (SEF) for ecosystems is a useful way to cushion adverse effects. In contrast to the conventional methods that take a minimum ecological flow as a constraint, studies have been conducted to establish multi-objective operation models with an ecological objective recently. This paper considers two cascaded reservoirs: the Three Gorges Project (TGP) and the Gezhouba Dam in the middle Yangtze River. By concentrating on urgent ecological problems such as the reproduction of four major species of Chinese carp and the propagation of Chinese sturgeon, a series of monthly SEF was synthesized. Afterward, a long-term multi-objective optimization model that maximizes power generation and minimizes the water volume that violates ecosystem water requirements was developed to study the relationship between the two objectives. The non-dominated sorting genetic algorithm II method was applied to solve the proposed model. The optimized results show that according to the present water control operating regulations, the monthly amount of released water of TGP can be sufficient for ecosystem requirements except in October. The ecological model is better in improving the river ecosystem, but at the expense of power generation loss. Moreover, this method provides a set of operational non-dominated schemes between the target objectives for decision-makers to select and could be useful for water resource management of reservoirs.

scholarly journals Impact of the Three Gorges Dam on sediment deposition and erosion in the middle Yangtze River: a case study of the Shashi Reach

2016 ◽  
Vol 47 (S1) ◽  
pp. 175-186 ◽  
Author(s):  
Wei Zhang ◽  
Jing Yuan ◽  
Jianqiao Han ◽  
Chengtao Huang ◽  
Ming Li
Keyword(s):  
Yangtze River ◽  
Shape Change ◽  
Three Gorges Dam ◽  
Three Gorges ◽  
Cross Sectional ◽  
The Three Gorges ◽  
Digital Elevation ◽  
Elevation Model ◽  
The Three Gorges Dam

Channel morphology in an alluvial river usually varies due to the altered flow and sediment regime from upstream damming. This paper reports an evaluation of the dynamical changes of sedimentation and erosion in the middle and lower reaches of the Yangtze River after operation of the Three Gorges Dam (TGD). Here, we present the results from a case study of the Shashi Reach in the middle Yangtze River, which is the first sandy-bed and meandering reach downstream of TGD. Databases were constructed using a digital elevation model of channel topography based on the 1:10,000 topographic maps from the 1980s to 2012 and hydrological records from 1956 to 2013. Results indicate that the erosion in the Shashi Reach was mainly confined to the deeper channel and that it has increased since the construction of the TGD. No significant changes were observed above the bank-full level, resulting in the decrease of the width-to-depth ratio. These changes may be principally caused by variations of the seasonal distribution of flow and sediment due to the operation of the dam. In addition, results show that the cross-sectional shape change of the channel is related to the relative erodibility of the channel bed and bank material.

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