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The multi-chamber Oscillating Water Column (OWC) device has recently become more attractive due to its potential high efficiency. In this paper, the hydrodynamic performance of a single-, dual- and triple-chamber OWC-breakwater are investigated experimentally. In the first instance, quantitative comparisons are implemented to understand the hydrodynamic performance of multi-chamber OWC-breakwaters. Specific attention has been dedicated to the hydrodynamic performance of capture width ratio (CWR), reflection coefficient, transmission coefficient, dissipation coefficient and effective frequency bandwidth. The investigation identified various findings that can be summarized as follows: i) hydrodynamic interactions between chambers in the multi-chamber OWC device has improved wave power extraction characteristics; ii) comparing with the conventional pontoon breakwater, the multi-chamber OWC-breakwater showed better wave attenuation performance in longer waves; iii) wave steepness is important for evaluating the performance of the multiple-chamber OWC-breakwater device; and iv) the implementation of the multi-chamber scheme broadens the effective frequency bandwidth (satisfied the condition of KT < 0.5 and η > 0.2) of OWC-breakwater.
Xuanlie Zhao; Lidong Zhang; Mingwei Li; Lars Johanning. Experimental investigation on the hydrodynamic performance of a multi-chamber OWC-breakwater. Renewable and Sustainable Energy Reviews 2021, 150, 111512 .
AMA StyleXuanlie Zhao, Lidong Zhang, Mingwei Li, Lars Johanning. Experimental investigation on the hydrodynamic performance of a multi-chamber OWC-breakwater. Renewable and Sustainable Energy Reviews. 2021; 150 ():111512.
Chicago/Turabian StyleXuanlie Zhao; Lidong Zhang; Mingwei Li; Lars Johanning. 2021. "Experimental investigation on the hydrodynamic performance of a multi-chamber OWC-breakwater." Renewable and Sustainable Energy Reviews 150, no. : 111512.
In this paper, the hydrodynamic performance of the comb-type breakwater-wave energy converter (CTB-WEC) system with a flange was investigated. Based on the linear potential flow theory, a semi-analytical model for wave interaction with the CTB-WEC system equipped with the flange was developed using matching eigenfunction method. In particular, Chebyshev polynomial was adopted to handle the singularity of velocity at the flange edge. Successful validation of the semi-analytical model was achieved by theoretical examination and comparing with the experimental data. The influence of wave resonance behavior in the confined water region (surrounded by caissons and the flange) was emphasized. It was found that: 1) the wave resonance behavior in the confined water region is modified due to the presence of the flange; 2) the hydrodynamic efficiency and wave attenuation performance of the CTB-WEC system is improved by properly configuring the flange; 3) the presence of piston and sloshing mode wave resonance in the gap between the WEC device and the flange led to the increment of hydrodynamic efficiency.
Xuanlie Zhao; Yang Zhang; Mingwei Li; Lars Johanning. Experimental and analytical investigation on hydrodynamic performance of the comb-type breakwater-wave energy converter system with a flange. Renewable Energy 2021, 172, 392 -407.
AMA StyleXuanlie Zhao, Yang Zhang, Mingwei Li, Lars Johanning. Experimental and analytical investigation on hydrodynamic performance of the comb-type breakwater-wave energy converter system with a flange. Renewable Energy. 2021; 172 ():392-407.
Chicago/Turabian StyleXuanlie Zhao; Yang Zhang; Mingwei Li; Lars Johanning. 2021. "Experimental and analytical investigation on hydrodynamic performance of the comb-type breakwater-wave energy converter system with a flange." Renewable Energy 172, no. : 392-407.
Based on linear potential flow theory, a semi-analytical model is developed using the matching eigenfunction method for a dual pontoon system in the presence of partially reflective seawall. To study the motion characteristics of an interconnected floating breakwater-wave energy converter system, the equations of motion in the frequency-domain are studied using the Lagrange-multiplier method. The model is verified using wave flux conservation law. A thorough investigation of the hydrodynamic performance of the integrated system is conducted, and the optimal power take-off damping of the system is derived theoretically. The results show that the proposed system exhibits a qualified wave power extraction performance and wave attenuation performance, and the presence of the seawall affects the performance of the integrated system significantly.
Xuanlie Zhao; Xin Du; Mingwei Li; Malin Göteman. Semi-analytical study on the hydrodynamic performance of an interconnected floating breakwater-WEC system in presence of the seawall. Applied Ocean Research 2021, 109, 102555 .
AMA StyleXuanlie Zhao, Xin Du, Mingwei Li, Malin Göteman. Semi-analytical study on the hydrodynamic performance of an interconnected floating breakwater-WEC system in presence of the seawall. Applied Ocean Research. 2021; 109 ():102555.
Chicago/Turabian StyleXuanlie Zhao; Xin Du; Mingwei Li; Malin Göteman. 2021. "Semi-analytical study on the hydrodynamic performance of an interconnected floating breakwater-WEC system in presence of the seawall." Applied Ocean Research 109, no. : 102555.
The bat algorithm (BA) has fast convergence, a simple structure, and strong search ability. However, the standard BA has poor local search ability in the late evolution stage because it references the historical speed; its population diversity also declines rapidly. Moreover, since it lacks a mutation mechanism, it easily falls into local optima. To improve its performance, this paper develops a hybrid approach to improving its evolution mechanism, local search mechanism, mutation mechanism, and other mechanisms. First, the quantum computing mechanism (QCM) is used to update the searching position in the BA to improve its global convergence. Secondly, the X-condition cloud generator is used to help individuals with better fitness values to increase the rate of convergence, with the sorting of individuals after a particular number of iterations; the individuals with poor fitness values are used to implement a 3D cat mapping chaotic disturbance mechanism to increase population diversity and thereby enable the BA to jump out of a local optimum. Thus, a hybrid optimization algorithm—the chaotic cloud quantum bats algorithm (CCQBA)—is proposed. To test the performance of the proposed CCQBA, it is compared with alternative algorithms. The evaluation functions are nine classical comparative functions. The results of the comparison demonstrate that the convergent accuracy and convergent speed of the proposed CCQBA are significantly better than those of the other algorithms. Thus, the proposed CCQBA represents a better method than others for solving complex problems.
Ming-Wei Li; Yu-Tain Wang; Jing Geng; Wei-Chiang Hong. Chaos cloud quantum bat hybrid optimization algorithm. Nonlinear Dynamics 2021, 103, 1167 -1193.
AMA StyleMing-Wei Li, Yu-Tain Wang, Jing Geng, Wei-Chiang Hong. Chaos cloud quantum bat hybrid optimization algorithm. Nonlinear Dynamics. 2021; 103 (1):1167-1193.
Chicago/Turabian StyleMing-Wei Li; Yu-Tain Wang; Jing Geng; Wei-Chiang Hong. 2021. "Chaos cloud quantum bat hybrid optimization algorithm." Nonlinear Dynamics 103, no. 1: 1167-1193.
A breakwater-WEC system combining heaving body Wave Energy Converters (WEC) and Comb-Type Breakwater (CTB) was investigated. The traditional CTB consists of a distributed array of separated bottom-mounted caissons and wave chambers are located between two caissons. Heaving bodies provide the power take off (PTO) principles that are arranged at the wave chamber of the CTB. The interaction of the CTB and WEC was investigated based on the linear potential flow theory. An analytical model has been developed to examine the hydrodynamic performance of CTB-WEC system. The analytical model is validated with results from an experimental study. Results show that an increase in conversion efficiency is observed when the device is located in the aft end of the wave chamber. A high efficiency (i.e., 77.4%) and qualified wave attenuation performance of the integrated system are achieved for the proposed CTB-WEC system. The wave resonance along the incident wave direction in the wave chamber is beneficial for wave energy capturing. Furthermore, it was found that the critical value kc corresponds to the wave resonance, perpendicular to the incident wave direction, out of the wave chamber. The property of efficiency mitigation at regions of k > kc should be avoided while designing such a system.
Xuanlie Zhao; Yang Zhang; Mingwei Li; Lars Johanning. Hydrodynamic performance of a Comb-Type Breakwater-WEC system: An analytical study. Renewable Energy 2020, 159, 33 -49.
AMA StyleXuanlie Zhao, Yang Zhang, Mingwei Li, Lars Johanning. Hydrodynamic performance of a Comb-Type Breakwater-WEC system: An analytical study. Renewable Energy. 2020; 159 ():33-49.
Chicago/Turabian StyleXuanlie Zhao; Yang Zhang; Mingwei Li; Lars Johanning. 2020. "Hydrodynamic performance of a Comb-Type Breakwater-WEC system: An analytical study." Renewable Energy 159, no. : 33-49.
This paper presents a model for forecasting the motion of a floating platform with satisfactory forecasting accuracy. First, owing to the complex nonlinear characteristics of a time series of floating platform motion data, a support vector regression model with a hybrid kernel function is used to simulate the motion of a floating platform. Second, the proposed chaotic efficient bat algorithm, based on the chaotic, niche search, and evolution mechanisms, is used to optimize the parameters of the hybrid kernel-based support vector regression model. Third, the ensemble empirical mode decomposition algorithm is utilized to decompose the original floating platform motion time series into a series of intrinsic mode functions and residuals. The ultimate forecasting results are obtained by summing the outputs of these functions. Subsequently, motion data for a real floating platform are used to evaluate the reliability and effectiveness of the proposed model.
Wei-Chiang Hong; Ming-Wei Li; Jing Geng; Yang Zhang. Novel chaotic bat algorithm for forecasting complex motion of floating platforms. Applied Mathematical Modelling 2019, 72, 425 -443.
AMA StyleWei-Chiang Hong, Ming-Wei Li, Jing Geng, Yang Zhang. Novel chaotic bat algorithm for forecasting complex motion of floating platforms. Applied Mathematical Modelling. 2019; 72 ():425-443.
Chicago/Turabian StyleWei-Chiang Hong; Ming-Wei Li; Jing Geng; Yang Zhang. 2019. "Novel chaotic bat algorithm for forecasting complex motion of floating platforms." Applied Mathematical Modelling 72, no. : 425-443.
Compared with a large power grid, a microgrid electric load (MEL) has the characteristics of strong nonlinearity, multiple factors, and large fluctuation, which lead to it being difficult to receive more accurate forecasting performances. To solve the abovementioned characteristics of a MEL time series, the least squares support vector machine (LS-SVR) hybridizing with meta-heuristic algorithms is applied to simulate the nonlinear system of a MEL time series. As it is known that the fruit fly optimization algorithm (FOA) has several embedded drawbacks that lead to problems, this paper applies a quantum computing mechanism (QCM) to empower each fruit fly to possess quantum behavior during the searching processes, i.e., a QFOA algorithm. Eventually, the cat chaotic mapping function is introduced into the QFOA algorithm, namely CQFOA, to implement the chaotic global perturbation strategy to help fruit flies to escape from the local optima while the population’s diversity is poor. Finally, a new MEL forecasting method, namely the LS-SVR-CQFOA model, is established by hybridizing the LS-SVR model with CQFOA. The experimental results illustrate that, in three datasets, the proposed LS-SVR-CQFOA model is superior to other alternative models, including BPNN (back-propagation neural networks), LS-SVR-CQPSO (LS-SVR with chaotic quantum particle swarm optimization algorithm), LS-SVR-CQTS (LS-SVR with chaotic quantum tabu search algorithm), LS-SVR-CQGA (LS-SVR with chaotic quantum genetic algorithm), LS-SVR-CQBA (LS-SVR with chaotic quantum bat algorithm), LS-SVR-FOA, and LS-SVR-QFOA models, in terms of forecasting accuracy indexes. In addition, it passes the significance test at a 97.5% confidence level.
Ming-Wei Li; Jing Geng; Wei-Chiang Hong; Yang Zhang. Hybridizing Chaotic and Quantum Mechanisms and Fruit Fly Optimization Algorithm with Least Squares Support Vector Regression Model in Electric Load Forecasting. Energies 2018, 11, 2226 .
AMA StyleMing-Wei Li, Jing Geng, Wei-Chiang Hong, Yang Zhang. Hybridizing Chaotic and Quantum Mechanisms and Fruit Fly Optimization Algorithm with Least Squares Support Vector Regression Model in Electric Load Forecasting. Energies. 2018; 11 (9):2226.
Chicago/Turabian StyleMing-Wei Li; Jing Geng; Wei-Chiang Hong; Yang Zhang. 2018. "Hybridizing Chaotic and Quantum Mechanisms and Fruit Fly Optimization Algorithm with Least Squares Support Vector Regression Model in Electric Load Forecasting." Energies 11, no. 9: 2226.
Hybridizing evolutionary algorithms with a support vector regression (SVR) model to conduct the electric load forecasting has demonstrated the superiorities in forecasting accuracy improvements. The recently proposed bat algorithm (BA), compared with classical GA and PSO algorithm, has greater potential in forecasting accuracy improvements. However, the original BA still suffers from the embedded drawbacks, including trapping in local optima and premature convergence. Hence, to continue exploring possible improvements of the original BA and to receive more appropriate parameters of an SVR model, this paper applies quantum computing mechanism to empower each bat to possess quantum behavior, then, employs the chaotic mapping function to execute the global chaotic disturbance process, to enlarge bat’s search space and to make the bat jump out from the local optima when population is over accumulation. This paper presents a novel load forecasting approach, namely SVRCQBA model, by hybridizing the SVR model with the quantum computing mechanism, chaotic mapping function, and BA, to receive higher forecasting accuracy. The numerical results demonstrate that the proposed SVRCQBA model is superior to other alternative models in terms of forecasting accuracy.
Ming-Wei Li; Jing Geng; Shumei Wang; Wei-Chiang Hong. Hybrid Chaotic Quantum Bat Algorithm with SVR in Electric Load Forecasting. Energies 2017, 10, 2180 .
AMA StyleMing-Wei Li, Jing Geng, Shumei Wang, Wei-Chiang Hong. Hybrid Chaotic Quantum Bat Algorithm with SVR in Electric Load Forecasting. Energies. 2017; 10 (12):2180.
Chicago/Turabian StyleMing-Wei Li; Jing Geng; Shumei Wang; Wei-Chiang Hong. 2017. "Hybrid Chaotic Quantum Bat Algorithm with SVR in Electric Load Forecasting." Energies 10, no. 12: 2180.