This paper aims at layout optimization design of obstacles in a three-dimensional T-type micromixer. Numerical analysis shows that the direction of flow velocity change constantly due to the ...obstacles blocking, which produces the chaotic convection and increases species mixing effectively. The orthogonal experiment method was applied for determining the effects of some key parameters on mixing efficiency. The weights in the order are: height of obstacles > geometric shape > symmetry = number of obstacles. Based on the optimized results, a multi-units obstacle micromixer was designed. Compared with T-type micromixer, the multi-units obstacle micromixer is more efficient, and more than 90% mixing efficiency were obtained for a wide range of peclet numbers. It can be demonstrated that the presented optimal design method of obstacles layout in three-dimensional microchannels is a simple and effective technology to improve species mixing in microfluidic devices. The obstacles layout methodology has the potential for applications in chemical engineering and bioengineering.
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•Layout optimization design of obstacles in a three-dimensional T-type micromixer has been achieved.•More than 90% mixing efficiency were obtained for a wide range of Peclet numbers.•The obstacles layout methodology has the potential for applications in chemical engineering and bioengineering.
Layout optimization of large-scale oil–gas gathering system is a kind of NP-hard problem in the field of system optimization. It involves a large number of network nodes, coupled optimization ...variables, complex network structures and hydraulic constraints, which cause the great difficulty in constructing optimization models and solution methods. In this paper, a high-dimensional mixed integer nonlinear layout optimization mathematical model involving the pipeline network structure parameters and pipeline design parameters is established, which can be applied to large-scale oil gathering system and gas gathering system universally. A modified particle swarm optimization (MPSO) algorithm with global search ability is proposed. The convergence theorem of the stochastic optimization algorithm is established based on the Poincare cycle theory. Global convergence of MPSO algorithm is proved, and the performance of MPSO algorithm is analyzed by numerical experiments. Based on dimension reduction planning and modularization thought, the grid dissection set partition method is proposed, and the theoretical foundation and complexity of the grid dissection method are discussed. In order to reduce the dimension of the layout optimization problem, the concept of the fuzzy set of adjacent position, and a novel approach for the well-station connection mode optimization are put forward. Based on the MPSO algorithm, grid dissection set partition method and solution method by fuzzy set of adjacent position, a combined optimization strategy for layout optimization model is proposed. The reliability and practicality of the proposed layout optimization model and combined optimization strategy are verified by the successful application of a real-world large-scale oil field with 661 wells.
•The continuous wake model describes well the wake profile behind a wind turbine.•The expected wind farm power is expressed as a differentiable function.•SCP can be employed to efficiently optimize ...the layout of a large-scale wind farm.•The optimized wind farm layout increases the wind farm power efficiency by 7.3%.
This paper describes an efficient method for optimizing the placement of wind turbines to maximize the expected wind farm power. In a wind farm, the energy production of the downstream wind turbines decreases due to reduced wind speed and increased level of turbulence caused by the wakes formed by the upstream wind turbines. As a result, the wake interference among wind turbines lower the overall power efficiency of the wind farm. To improve the overall efficiency of a wind farm, researchers have studied the wind farm layout optimization problem to find the placement locations of wind turbines that maximize the expected wind farm power. Most studies on wind farm layout optimization employ heuristic search-based optimization algorithms. In spite of their simplicity, optimization algorithms based on heuristic search are computationally expensive and have limitation in optimizing the locations of a large number of wind turbines since the computational time for the search tends to increase exponentially with increasing number of wind turbines. This study employs a mathematical optimization scheme to efficiently and effectively optimize the locations of a large number of wind turbines with respect to maximizing the wind farm power production. To formulate the mathematical optimization problem, we derive a continuous wake model and express the expected wind farm power as a continuous and smooth function in terms of the locations of the wind turbines. The constructed wind farm power function is then maximized using sequential convex programming (SCP) for the nonlinear mathematical problem. We show how SCP can be used to evaluate the efficiency of an existing wind farm and to optimize a wind farm layout consisting of 80 wind turbines.
•A new engineering wake model for wind farm in complex terrain is proposed.•The new model yields accurate results comparable to CFD simulation and is fast to run.•Systematic comparison of eight ...algorithms is done for wind farm layout optimization.•Random search, local search and pattern search are found to be the best algorithms.
Layout optimization of wind farms constitutes an important and challenging task in complex terrain. This is especially due to the complex interactions of the boundary layer flows in complex terrain and wind turbine wakes, which renders wake modelling in complex terrain difficult. This study tackles this challenge with a new engineering wake model, which is developed by superposing a Gaussian shape wake model on top of the background flow field, assuming that the centerlines of wind turbine wakes follow the streamlines of the background flow field. The model is found to predict wind turbine wakes in complex terrain with good accuracy and at the same time it is computationally cheap to run for optimization applications. Comparisons with high fidelity simulations and field measurements for a real wind farm with 25 turbines in complex terrain demonstrate its effectiveness. A systematic comparison of eight optimization algorithms, which includes two gradient-based and six gradient-free algorithms, is also carried out for the layout optimization problem in complex terrain. To accelerate the optimization process, a double-stage approach is proposed, which optimizes the objective function first neglecting wake effects and then, in the second stage, including them. While all the tested optimization algorithms can improve the original wind farm layout, random search, local search, and pattern search are found to be the top three algorithms in terms of optimization results and computational cost.
•A measurement-based method for determining optimal support layout is proposed.•Only a small number of modal parameters need to be measured in this method.•This method can reduce responses of a ...post-manufactured pipeline at resonance.•The proposed method is demonstrated on a real L-shaped pipeline system.
Layout optimization of elastic supports is an effective approach to address the resonance problem of an industrial post-manufactured pipeline. However, previous investigations of support layout optimization of a post-manufactured pipeline usually require establishing or updating the numerical model of the whole pipeline system, which may lead to time-consuming calculations and poor optimization results. In order to overcome these drawbacks, a new measurement-based layout optimization method is proposed in this method. Only a small number of experimental modal parameters (natural frequencies, damping ratios, and mode shapes) are needed in this method. Resonance avoidance, in this method, is recast as an assignment of natural frequencies, and the target natural frequencies are realized by performing structural modification in two stages. In addition, each of the elastic supports is viewed as a mass-spring-damper sub-system in this paper, which is represented by its measured dynamic stiffness and does not need a pre-determined simplified form. A numerical example demonstrates that the proposed method can accurately realize the target natural frequencies. The application of the proposed method to optimize the support layout of a real L-shaped pipeline system provides experimental evidence of its effectiveness. This experiment is the first attempt to achieve the layout optimization of pipeline supports for solving the resonance problem of a post-manufacture pipeline, entirely relying on the measured modal data.
The production efficiency and optimal control of wave energy converter (WEC) array are mainly based on array layout, thus it is crucial to establish a reliable mathematical model for the WEC array ...layout optimization. So far, a lot of research has been done on the modeling and methods of WEC array layout optimization. However, the existing reviews are either incomplete in the classification of modeling methods, or incomplete in a collection of optimization methods, especially lacking detailed evaluation. This paper aims to comprehensively summarize various WEC models and related approaches for WEC array layout optimization. Note that over 80 related pieces of literature have been carefully analyzed and summarized, and they are divided into three categories: meta-heuristic-based, machine learning-based, and mathematics-based methods. In particular, the advantages/disadvantages, variables, evaluation indices, parameters, complexity, and objective functions are thoroughly discussed. Finally, potential research directions and recommendations are proposed in future in-depth research for both researchers and engineers.
•Summarize nine models for WEC array layout optimization.•Advantages/disadvantages and evaluation criteria of models are summarized.•Present the advantages/disadvantages of all methods.•Five invaluable and insightful perspectives/recommendations are proposed.
•Simultaneous optimization of wind farm’s network layout and cable cross-sections.•Proposed method brings substantial cost savings compared with other methods.•Usefulness and effectiveness of the ...MILP optimization was demonstrated.•Electrical losses need to be taken into account in the design process.•An absolute optimal solution (GAP=0) is received in a reasonable computation time.
Internal electrical networks of large wind farms constitute complex and dispersed grid structures. Wind turbines are scattered over vast areas and the total length of cabling infrastructure might reach several dozens of kilometers. Outlays related to cable laying significantly contribute to the entire project budget. Therefore the design process should minimize these expenses considering also operation and maintenance costs calculated over the project lifetime on condition of fulfilment of all technical requirements. An analysis presented in this paper demonstrates that an independent optimization of the twofold problem dealing both with investment and operation costs does not result in the cheapest solution. The analysis confirmed also reliability and effectiveness of application of Mixed Integer Linear Programming method (MILP) to solve this kind of optimization problem. The paper shows that the developed integrated optimization algorithm is efficient and delivers an absolute optimal solution (GAP=0) in a reasonable computation time. The results obtained for a real wind farm project confirm that the optimal design of a wind farm network can’t be determined a priori and the final outcome strongly depends on the configuration of wind turbines (e.g., number of feeders, number of turbines connected to a single feeder, etc.) and technical parameters of cables. Spread over time, discounted costs of energy losses are an integral part of the objective function. The study proves that cost of energy losses impacts on the overall financial results and shouldn’t be neglected. The related expenses are roughly at the same level as expenditure linked to cable laying and they heavily influence the final design of the internal network. The results show the possibility of practical use of the proposed algorithm in the wind farm design process.
•An novel multi-objective model is proposed for the optimal transmission lines layout.•Impacts of energy storage and demand response in RE power integration are explored.•Eleven types of DC and AC ...transmission technologies are considered.•The stability of transmission network is modeled from the macro level.
To eliminate power transmission bottleneck and improve cross-regional consumption of renewable power in China, a multi-objective optimization model for transmission line layout is established by considering grid stability and the flexible resource. The optimal line route, technology selection among eleven types of direct current (DC) and alternating current (AC) transmission technologies, transmission capacity, and completion time of inter-regional transmission lines among the six major regions are determined. The results show that power transmission capacity of Northwest-to-East and North-to-Central will increase by 265% and 160%, respectively, in 2039, compared with that in 2018. DC of 800 kV (10 GW) will become the main transmission technology from 2033. The peak period of the line-construction completion will be 2036–2039. The central and eastern regions have registered the fastest growth in the proportion of wind and solar power-installed capacity in China. The proportion of wind and solar power-installed capacity in these areas in 2039 will be 4–6 times that in 2018. Increasing energy storage and improving demand-side response can increase the on-grid renewable power by 1.7% and 2.6%, respectively; however, it will lead to a reduction of 2–6 and 7–9 newly-built lines, respectively.
Rapid urbanization has had a profound impact on rural socioeconomic development, which has driven the spatial restructuring of rural settlements. Numerous studies have analyzed the spatial ...restructuring of rural settlements, yet socioeconomic factors and their impacts on villages and rural settlements have been ignored. This paper implemented a dual-scale coupling approach to identify the restructuring direction of rural settlements in Tingzu Town, Hubei Province, China. At the village scale, a population-land-industry evaluation index system was constructed to calculate the development potential of villages. The advanced gravity model was used to measure the intervillage connections, and K-means clustering was applied to divide the village groups, both approaches were used to identify the central villages. At the patch scale, kernel density estimation and accessibility analysis were applied to identify the spatial distribution characteristics of rural settlements, and rural settlements were classified into nine types based on the analysis of density-accessibility spatial combination characteristics. Four types, including relocation and evacuation, characteristic protection, suburban integration, and agglomeration and upgrading were proposed to restructure rural settlements. The restructuring direction and strategies of each type were determined by combining the influence scope of each central village, delineated by the weighted Voronoi diagram and the actual development needs of rural settlements. This study contributes to our understanding of the relationship involved in the restructuring of rural settlements and is of great practical significance for guiding the optimization of rural settlement layouts.
•The spatial restructuring of rural settlements was analyzed at dual scale.•Intervillage connections were measured using the advanced gravity model.•Density-accessibility combination characteristics were analyzed at the patch scale.•Four types of rural settlements and their restructuring directions were identified.
The wind farm layout optimization problem has received considerable attention over the past two decades. The objective of this problem is to determine the wind farm layout that maximizes the annual ...energy generated. The majority of studies that have solved this problem simulated the velocity deficit using the Jensen wake model. However, this model is not in agreement with field measurements and computational fluid dynamics simulations. In this study, an approach to solve the wind farm layout optimization problem based on a Gaussian wake model is proposed. The Gaussian wake model uses an exponential function to evaluate the velocity deficit, in contrast to the Jensen wake model that assumes a uniform velocity profile inside the wake. The proposed approach minimizes the annual cost of energy of a wind farm using a genetic algorithm. The application of the proposed approach yields higher annual generation and a lower computational time for all wind scenarios under study. Under a more complex wind scenario, the improvement was relatively small. This suggests that the use of a more robust wake model in the WFLO problem, does not lead to greater efficiency in real wind cases.
•A robust approach for the wind farm layout optimization problem is proposed.•The performance of a Gaussian-based wake model is compared to a top-hat wake model.•The proposed approach minimizes the annual cost of energy using a genetic algorithm.•Under a constant wind scenario, more efficient wind farms are obtained.•The improvement is small under more complex wind scenarios.
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