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Collective control in arrays of wave energy converters

RENEWABLE ENERGY 2020年 156卷 361-369页

作者： Zou, Shangyan Abdelkhalik, Ossama Iowa State Univ Dept Aerosp Engn Ames IA 50011 USA

A Collective Control is developed in this paper for arrays of Wave Energy Converters (WECs). The proposed controller applies a Proportional-Derivative feedback control law for each WEC with the optimized controller gains. A surrogate model, composed of only mechanical elements, is adopted to replace the hydrodynamic model during the optimization process. An indirect exterior penalty function approach is implemented to handle the constraints on the displacement and control. The weight of the penalty function is updated in subsequent iterations in the sequential unconstrained minimization technique. A numerical simulation is first conducted for identification of the surrogate model parameters. With the control gains optimized based on the surrogate model, the energy conversion is compared for three models: the surrogate model, a model that uses a boundary element tool to compute the hydrodynamic forces, and a simulation using AQWA. The results show a good agreement of the energy conversion among the models. Finally, the performance of the surrogate model is analyzed. It is shown that the proposed controller maximizes the energy conversion of the entire WEC array while satisfying the constraints. Moreover, the surrogate model can replace the hydrodynamic model to predict the system behavior with adequate accuracy and more efficiency. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Wave energy conversion Wave energy converters array Collective control Surrogate model sequential unconstrained minimization technique

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Collaborative Estimation and Actuation for Wireless Sensor and Actuator Networks

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IFAC Proceedings Volumes 2014年第3期47卷 5544-5549页

作者： Lei Mo Xianghui Cao Jiming Chen Youxian Sun State Key Lab. of Industrial Control Technology Zhejiang University Hangzhou 310027 China

Wireless sensor and actuator networks (WSANs) facilitate close interactions between human and the environment. Efficient coordination among the sensors and actuators plays a vital role in carrying out sensing and acting in WSANs. In this paper, we develop a collaborative estimation and actuation mechanism, which consists of a sensor-actuator coordination phase and an actuator-actuator coordination phase. The first phase is based on distributed Kalman filter in federated configuration, which is able to provide reliable and precise sensing data. On this basis, the second phase allocates proper tasks based on system requirements and coordinates actuators to accomplish the tasks. Particularly, the actuator-actuator coordination is formulated as an optimization problem and an effective method is proposed to search the solution based on sequential unconstrained minimization technique. Simulation results demonstrate the effectiveness of our proposed mechanism.

关键词： Wireless sensor and actuator networks node coordination federated Kalman filter actuator task allocation sequential unconstrained minimization technique

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Shape optimization of structures for frequency constraints by sequential harmony search algorithm

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ENGINEERING OPTIMIZATION 2013年第6期45卷 627-646页

作者： Gholizadeh, S. Barzegar, A. Urmia Univ Dept Civil Engn Orumiyeh Iran

Shape optimization of structures with frequency constraints is a highly nonlinear dynamic optimization problem. In order to deal with this type of optimization problem, efficient optimization algorithms should be employed. The main objective of the present study is to propose an efficient harmony search (HS)-based algorithm for solving the shape optimization problem of pin-jointed structures subject to multiple natural frequency constraints. In the proposed algorithm an enhanced version of HS is employed in the framework of the sequential unconstrained minimization technique. The efficiency of the presented sequential harmony search (SHS) algorithm is illustrated through several benchmark optimization examples and the results are compared to those of different optimization techniques. The numerical results demonstrate the computational advantages of the SHS in shape optimization of structures for frequency constraints.

关键词： shape optimization harmony search algorithm frequency constraint sequential unconstrained minimization technique

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Estimation of Border-Strip Soil Hydraulic Parameters

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JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING 2012年第6期138卷 493-502页

作者： Ram, Shobha Prasad, K. S. Hari Gairola, Ajai Jose, M. K. Trivedi, M. K. Indian Inst Technol Dept Civil Engn Roorkee 247667 Uttarakhand India Natl Inst Hydrol Roorkee 247667 Uttarakhand India Reg Ctr BELGAUM Natl Inst Hydrol Belgaum 590001 Karnataka India Madhav Inst Sci & Technol Dept Civil Engn Gwalior Madhya Pradesh India

The inverse problem of determining soil hydraulic parameters (saturated hydraulic conductivity and water retention parameters) of border-strip irrigation from irrigation event data is analyzed. The inverse problem is solved using sequential unconstrained minimization technique. The forward problem involves the solution of coupled Saint-Venant's equation governing overland flow and Richard's equation governing subsurface flow. Saint-Venant's equations are solved using the MacCormack scheme-based finite-difference method while Richard's equation is solved using a mass conservative fully implicit finite-difference method. Field experiments are conducted on two border strips to obtain surface and subsurface irrigation data such as irrigation advance, recession, flow depth, and soil moisture content. The soil hydraulic parameters, i.e., saturated hydraulic conductivity and soil retention parameters, are estimated by minimizing the deviations between the model-predicted and field-observed irrigation data. The results indicate that defining the objective function in terms of flow depths results in the optimization algorithm converging to the true values as compared to the use of irrigation advance data. Further, it is observed that underestimating the initial guess results in the least number of iterations for the optimization algorithm to converge to the true values. It is also observed that simultaneous estimation of all three soil hydraulic parameters is not possible even with the inclusion of subsurface moisture content data in the objective function. DOI: 10.1061/(ASCE)IR.1943-4774.0000398. (C) 2012 American Society of Civil Engineers.

关键词： Border-strip irrigation Identifiability Parameter estimation Least-squares minimization sequential unconstrained minimization technique

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Estimation of water cloud model vegetation parameters using a genetic algorithm

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HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES 2012年第4期57卷 776-789页

作者： Kumar, Kamal Prasad, K. S. Hari Arora, M. K. Indian Inst Technol Roorkee Dept Civil Engn Roorkee 247667 Uttar Pradesh India

The water cloud model is used to account for the effect of vegetation water content on radar backscatter data. The model generally comprises two parameters that characterize the vegetated terrain, A and B, and two bare soil parameters, C and D. In the present study, parameters A and B were estimated using a genetic algorithm (GA) optimization technique and compared with estimates obtained by the sequential unconstrained minimization technique (SUMT) from measured backscatter data. The parameter estimation was formulated as a least squares optimization problem by minimizing the deviations between the backscatter coefficients retrieved from the ENVISAT ASAR image and those predicted by the water cloud model. The bias induced by three different objective functions was statistically analysed by generating synthetic backscatter data. It was observed that, when the backscatter coefficient data contain no errors, the objective functions do not induce any bias in the parameter estimation and the true parameters are uniquely identified. However, in the presence of noise, these objective functions induce bias in the parameter estimates. For the cases considered, the objective function based on the sum of squares of normalized deviations with respect to the computed backscatter coefficient resulted in the best possible estimates. A comparison of the GA technique with the SUMT was undertaken in estimating the water cloud model parameters. For the case considered, the GA technique performed better than the SUMT in parameter estimation, where the root mean squared error obtained from the GA was about half of that obtained by the SUMT.

关键词： vegetation parameter backscatter coefficient inverse problem genetic algorithm data errors bias root mean squared error sequential unconstrained minimization technique

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Optimization of Rolling Schedule in Tandem Cold Mill Based on QPSO Algorithm

Optimization of Rolling Schedule in Tandem Cold Mill Based o...

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International Symposium on Advanced Rolling Equipment and Technologies

作者： Lin, Sen Nan, Yurong Zhejiang Univ Technol Hangzhou 310014 Zhejiang Peoples R China

ISBN: (纸本)9780878492190

This paper adopts equal relatively load as objective function, and makes every parameter to meet certain restrictive conditions. SUMT algorithm was used to change constraints to non-binding conditions. QPSO algorithm was applied to optimize objective functions to obtain optimal solution. This algorithm was based on classical particle swarm optimization, which, with the conduct of quantum particle, had effective global search capability, good convergence and stability. As a result, reasonable distribution of tandem cold rolling power and full use of equipment capacity were realized, resulting in the improvement of production efficiency.

关键词： Tandem cold rolling Schedule optimization Quantum particle swarm optimization sequential unconstrained minimization technique

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Economic Analysis of the SUMT to Optimal Design Portal Frame

Economic Analysis of the SUMT to Optimal Design Portal Frame

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2011 International Conference on Business Management and Electronic Information(BMEI 2011)

作者： Lin Xian-gen College of Urban Constrction Zhejiang Shuren University, Hangzhou 3 0015,China

Alone with the application of computer technology, the growing needs of modern design and productivity development, optimal design theory has been widely used in practical design projects. In this paper, sequential unconstrained minimization technique (SUMT) is used as a means of studying single-span portal frame optimal design, which brings about favorable results. Such method can be consulted and used by technicians and managers in related areas.

关键词： optimal design sequential unconstrained minimization technique I-steel portal frame variable crosssection Economic Analysis

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Generalized Hopfield network based structural optimization using sequential unconstrained minimization technique with additional penalty strategy

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ADVANCES IN ENGINEERING SOFTWARE 2002年第7-10期33卷 721-729页

作者： Shih, CJ Yang, YC Tamkang Univ Dept Mech Engn Tamsui 25137 Taiwan

This paper presents and examines a neuron-like framework of the generalized Hopfield network (GHN) that is capable to solve nonlinear engineering optimization problems with mixed discrete, integer and real continuous variables. The sequential unconstrained minimization technique (SUMT) was applied to construct the GHN for dealing with the design constraints. An additional penalty function for dealing with the discrete and integer variables was then imposed on the formulation of SUMT to construct an energy function of GHN for formulating the neuron-like dynamical system. The numerical solution process for such a dynamic system is simply solving a set of simultaneous first-order ordinary differential equations (ODE) that is the main feature of this optimization method. The experimental examples showed the presenting strategy is reliable. The suitable values or the adaptation technique for some parameters in computation was discussed in the paper. The presenting strategy indeed provides an alternative way of handling the engineering optimization dynamically and expands the usage of ODE. An asymmetrical three-bar truss design, a reinforced concrete beam design and a 10-bar structural design are contributed to illustrate the presenting neuron-like network method. (C) 2002 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved.

关键词： generalized Hopfield network nonlinear programming sequential unconstrained minimization technique penalty function ordinary differential equation structural optimization

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Reliability based optimization of submarine pressure hulls with inelastic interstiffener buckling failure

Reliability based optimization of submarine pressure hulls w...

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25th International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2006)

作者： Radha, P. Rajagopalan, K. Indian Inst Technol Dept Ocean Engn Madras 600036 Tamil Nadu India

ISBN: (纸本)9780791847480

Uncertainties that exist in modelling and simulation, design variables and parameters, manufacturing processes etc., may lead to large variations in the performance characteristics of the system. Optimized deterministic designs determined without considering uncertainties can be unreliable and nay lead to catastrophic failure of the structure being designed. Reliability based optimization (RBO) is a methodology that addresses these problems. In this paper the reliability based optimization of submarine pressure hulls in which the failure gets governed by inelastic interstiffener buckling has been described. The problem has been formulated to minimize the ratio of weight of shell-stiffener geometry to the weight of liquid displaced, subjected to reliability based inelastic interstiffener buckling constraint. Since the methods of analysis of inelastic buckling failure of submarine pressure hulls are inadequate, in the present study the Johnson-Ostenfeld inelastic correction method has been adopted for formulating the constraint. By considering spacing of the stiffener, thickness of the plating and depth of the stiffener as the design variables, sequential unconstrained minimization technique (SUMT) has been used to solve the design problem. RBO has been carried out to get the optimal values of these design variables for a target reliability index using Interior Penalty Function Method for which an efficient computer code in C++ has been developed.

关键词： reliability based optimization sequential unconstrained minimization technique inelastic buckling penalty function method submarine pressure hulls

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Generalized Hopfield network based structural optimization using sequential unconstrained minimization technique with additional penalty strategy

Generalized Hopfield network based structural optimization u...

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2nd International Conference on Engineering Computational Technology/5th International Conference on Computational Structures Technology

作者： Shih, CJ Yang, YC Tamkang Univ Dept Mech Engn Tamsui 25137 Taiwan

关键词： generalized Hopfield network nonlinear programming sequential unconstrained minimization technique penalty function ordinary differential equation structural optimization

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