SDDOM 2013 Abstracts

Full Papers Short Papers
Full Papers
Paper Nr: 3
Title:

Surrogate Modeling and Optimization of Inline E-plane Waveguide Extracted Pole Filters
Authors:

Oleksandr Glubokov, Slawomir Koziel and Leifur Leifsson
Abstract: The paper presents an optimization procedure for inline e-Plane waveguide extracted pole filters with all-metal inserts. The main focus is on the development of the schematic circuit based surrogate model for this class of filters. The model proposed here takes into account couplings between adjacent elements of the structure, which is crucial for obtaining sufficient accuracy. The circuit model is subsequently used in the surrogate-based optimization of the filter structure. Filter optimization is carried out using space mapping as the main engine and the aforementioned circuit representation as an underlying coarse model. Specific filter design cases are considered to verify the proposed procedure. It is demonstrated that the optimized designs can be obtained at a low computational cost corresponding to a few evaluations of the high-fidelity EM simulations of the filter structures of interest.
Paper Nr: 4
Title:

Design of Antenna Arrays using Surrogate-based Optimization
Authors:

Slawomir Koziel, Stanislav Ogurtsov and Leifur Leifsson
Abstract: Design of planar arrays of microstrip antennas using full-wave electromagnetic (EM) simulation and surrogate-based optimization (SBO) is considered. The design goals include reduction of the sidelobe levels and keeping reflection signals low (= -10dB) at the array element terminals. Our approach exploits a low-fidelity EM simulation model of the array used as a prediction tool that, after suitable correction, guides the optimization process towards the high-fidelity EM model optimum. The design process starts from a uniform array configuration and comprises two major stages: radiation pattern optimization and reflection/mutual coupling minimization. Our technique is demonstrated using 25-element array. Despite a large number of designable parameters, the optimized design is obtained at the cost of 15 equivalent high-fidelity EM simulations of the entire array. Further reduction of the design cost can be obtained by using an analytical model of the array directivity pattern that embeds the simulated radiation response of the single microstrip patch antenna. As an illustration, the optimized design for the 7 × 7 (49 elements) microstrip array is obtained at the computational cost corresponding to only about 5 evaluations of the high-fidelity array model.
Paper Nr: 5
Title:

Low-cost Modeling of Waveguide Filters using Decomposition and Space Mapping
Authors:

Slawomir Koziel, Stanislav Ogurtsov and Leifur Leifsson
Abstract: A technique for low cost surrogate modeling of waveguide filters is presented. Our approach is based on the decomposition of the filter structure. Some of the decomposed parts are modeled using response surface approximations (RSAs). The RSA models are subsequently combined with the analytical models of the waveguide sections into the initial filter surrogate. Due to electromagnetic coupling between the decomposed parts, which is not accounted for by the initial surrogate, its accuracy is limited. This misalignment is reduced by applying space mapping at the level of the complete filter structure. Decomposition approach allows us to greatly reduce the computational cost of creating the surrogate because the simulation time of the parts of the structure is much lower than for the entire filter and, more importantly, the number of parameters describing the parts are lower than for the entire filter. The presented technique is demonstrated using two test cases. Application examples are also given.
Paper Nr: 6
Title:

Efficient Quantile Estimators for River Bed Morphodynamics
Authors:

T. Clees, I. Nikitin, L. Nikitina and S. Pott
Abstract: The large impact of civil water engineering to nature and society imposes high requirements for the precision of numerical simulations used in planning and evaluation of river engineering concepts. In particular, coupled morphodynamic - hydrodynamic simulation uses models of river bed evolution possessing uncertain parameters. The sources of uncertainty can be the natural variability, the deficient description of the physical processes in the model and the imprecision of the model parameters. The propagation of these uncertainties to the variance of the model result can be quantified with the aid of stochastic analysis. Precise evaluation of stochastic characteristics normally requires a huge amount of samples, which can be provided by surrogate-based modeling of simulation results. In this paper we present our advances in quantile estimation of morphodynamic simulations of river bed evolution. We use metamodeling of bulky simulation results with radial basis functions (RBF), quasi-Monte Carlo sampling (QMC) and efficient quantile estimator (QE). Four different quantile estimators have been tested. A realistic application case is used to demonstrate the efficiency of the approach.
Paper Nr: 7
Title:

Multi-objective Optimization of Axial Flow Pump based on Modified PSO Algorithm
Authors:

H. S. Park and Fu-qing Miao
Abstract: In axial flow pump design process, in order to get high performance pump, designers usually try to increase the efficiency (?) and decrease the required NPSH (NPSHr) simultaneously. In this paper, multi-objective optimization of axial flow pump based on modified Particle Swarm Optimization (MPSO) is performed. At first, the NPSHr and ? in a set of axial flow pump are numerically investigated using commercial software ANSYS with the design variables concerning hub angle ß_h, chord angle ß_c, cascade solidity of chord s_c, maximum thickness of blade H. And then, using the Group Method of Data Handling (GMDH) type neural networks in commercial software DTREG, the corresponding polynomial representation for NPSHr and ? with respect to design variables are obtained. Finally, multi objective optimization based on modified Particle Swarm Optimization (MPSO) approach is used for Pareto based optimization. The result shows that an optimal solution of the axial flow pump impeller was obtained: NPSHr was decreased by 11.68% and efficiency was increased by 4.24% simultaneously. It means this optimization is feasible.
Paper Nr: 8
Title:

Hydrodynamic Design Optimization of Trawl-door Shapes with Local Surrogate Models
Authors:

Elvar Hermannsson, Leifur Leifsson, Slawomir Koziel, Stanislav Ogurtsov, Oleksandr Glubokov and Reza Fakhraie
Abstract: Trawl-doors have a large influence on the fuel consumption of fishing vessels. Design and optimization of trawl-doors using computational models are a key factor in minimizing the fuel consumption. This paper presents an optimization algorithm for the shape design of trawl-door shapes using computational fluid dynamic (CFD) models. Accurate CFD models are computationally expensive. Therefore, the direct use of traditional optimization algorithms, which often require a large number of evaluations, may prohibitive. The proposed approach is iterative and uses low-order local response surface approximation models of the expensive CFD model, constructed in each iteration, to reduce the number of evaluations. The algorithm is applied to the design of a two-element trawl-door (slat and airfoil), involving four design variables controlling the angle of attack and the slat position and orientation. The results show that a satisfactory design can be obtained at the cost of a few iterations of the algorithm.
Paper Nr: 10
Title:

Variable-fidelity Aerodynamic Optimization using CFD Models
Authors:

Leifur Leifsson, Slawomir Koziel, Stanislav Ogurtsov and Oleksandr Glubokov
Abstract: A brief review of some recent variable-fidelity aerodynamic shape optimization methods is presented. We discuss three techniques that—by exploiting information embedded in low-fidelity computational fluid dynamics (CFD) models—are able to yield a satisfactory design at a low computational cost, usually corresponding to a few evaluations of the original, high-fidelity CFD model to be optimized. The specific techniques considered here include multi-level design optimization, space mapping, and shape-preserving response prediction. All of them use the same prediction-correction scheme, however, they differ in the way the low-fidelity model information it utilized to construct the surrogate model. The presented techniques are illustrated using two specific cases of transonic airfoil design involving lift maximization and drag minimization.
Paper Nr: 11
Title:

Efficient Kriging-based Robust Optimization of Unconstrained Problems
Authors:

Samee ur Rehman, Matthijs Langelaar and Fred van Keulen
Abstract: In this paper, we use Kriging and expected improvement to apply robust optimization on unconstrained problems affected by implementation error. A two-stage process is employed, where, at the first stage, a response surface of the nominal function is fitted using a design of experiments strategy such as Latin hypercube sampling (LHS). Based on this response surface, in each iteration, we construct a worst-case cost metamodel by finding the maximum realizable value of the objective with respect to the uncertainty set on the nominal metamodel. We use the total Kriging error estimate of the two metamodels to find an appropriate expected improvement criterion for robust optimization. A new sample is added at each iteration by finding the location at which this modified expected improvement measure is maximum. By means of this process, we iteratively move towards the robust optimum. We test the efficiency and convergence of the algorithm by performing hundred runs of the considered test problem for different initial sampling. These results show that the algorithm converges to the robust optimum consistently.
Short Papers
Paper Nr: 9
Title:

Implication of Fuels in Performance of Single-stage Launch Vehicle with Hybrid Rocket Engine
Authors:

Kazuhisa Chiba, Masahiro Kanazaki, Koki Kitagawa and Toru Shimada
Abstract: A single-stage hybrid rocket is necessary in order to efficiently perform the scientific observations and experiments. The primary objective of the present conceptual design is that the sufficient downrange and duration time in the low thermosphere is obtained in order to efficiently observe aurora, which is one of the recent topics in the scientific area, as well as holding down initial gross weight. The achievement of the mission as the observation of aurora using single-stage launch vehicle with hybrid rocket engine has been investigated by using design informatics. Moreover, the implication of fuels for the design requirements has also been investigated. As a result, the design information regarding the relationship among the design requirements, the influence regarding design variables for design requirements, and also implications of solid fuels for the performance were revealed.