Nature-Inspired Algorithms in Optimization: Introduction, Hybridization and Insights

Many problems in science and engineering are optimization problems, which may require sophisticated optimization techniques to solve. Nature-inspired algorithms are a class of metaheuristic algorithms for optimization, and some algorithms or variants are often developed by hybridization. Benchmarking is also important in evaluating the performance of optimization algorithms. This chapter focuses on the overview of optimization, nature-inspired algorithms and the role of hybridization. We will also highlight some issues with hybridization of algorithms.Comment: 15 pages, 4 figure

Integrated Infrastructure Modelling — Managing Interdependencies with a Generic Approach

Infrastructure provision is a highly challenging task, especially when accounting for climate change mitigation and adaptation needs. Efforts of making infrastructure more efficient and flexible result in an increasing number of sensitive infrastructure interdependencies. This enforces an integrated infrastructure assessment for planning purposes, in contrast to the traditional independent infrastructure-sector modelling. For the unification of the existing infrastructure-sector models, we propose the implementation of a generic communication interface, which allows the separate sector-models to communicate at the necessarily disaggregate level in order to account for interdependencies appropriately. This approach allows for infrastructure provision modelling under one unified umbrella in a minimally invasive way, while conserving crucial individualities of the separate models. This is achieved through a generic network description, in which we solve the resource allocation through a pragmatic network-flow algorithm that resembles market and consumer behaviour. The developed framework establishes the basis for fully integrated infrastructure evaluation and hence cross-sectorial infrastructure investment decision making — a crucial tool in times of tight governmental budgets

Electret-based cantilever energy harvester: design and optimization

We report in this paper the design, the optimization and the fabrication of an electret-based cantilever energy harvester. We develop the mechanical and the electrostatic equations of such a device and its implementation using Finite Elements (FEM) and Matlab in order to get an accurate model. This model is then used in an optimization process. A macroscopic prototype (3.2cm^{2}) was built with a silicon cantilever and a Teflon\textregistered electret. Thanks to this prototype, we manage to harvest 17\muW with ambient-type vibrations of 0.2g on a load of 210M{\Omega}. The experimental results are consistent with simulation results

Accelerated Methods for α\alpha-Weakly-Quasi-Convex Problems

Many problems encountered in training neural networks are non-convex. However, some of them satisfy conditions weaker than convexity, but which are still sufficient to guarantee the convergence of some first-order methods. In our work we show that some previously known first-order methods retain their convergence rates under these weaker conditions

The economically optimal design of heat exchangers

A new method to design heat exchangers is proposed, which is based on the process description by Kays and London and lends itself very well to optimization.\ud The method is described by applying it to the economic optimization of a counter-current exchanger, the extension to other flow configurations being selfexplanatory.\u

Design and analysis considerations for deployment mechanisms in a space environment

On the second flight of the INTELSAT V spacecraft the time required for successful deployment of the north solar array was longer than originally predicted. The south solar array deployed as predicted. As a result of the difference in deployment times a series of experiments was conducted to locate the cause of the difference. Deployment rate sensitivity to hinge friction and temperature levels was investigated. A digital computer simulation of the deployment was created to evaluate the effects of parameter changes on deployment. Hinge design was optimized for nominal solar array deployment time for future INTELSAT V satellites. The nominal deployment times of both solar arrays on the third flight of INTELSAT V confirms the validity of the simulation and design optimization

On a novel approach for optimizing composite materials panel using surrogate models

This paper describes an optimization procedure to design thermoplastic composite panels under axial compressive load conditions. Minimum weight is the goal. The panel design is subject to buckling constraints. The presence of the bending-twisting coupling and of particular boundary conditions does not allow an analytical solution for the critical buckling load. Surrogate models are used to approximate the buckling response of the plate in a fast and reliable way. Therefore, two surrogate models are compared to study their effectiveness in composite optimization. The first one is a linear approximation based on the buckling constitutive equation. The second consists in the application of the Kriging surrogate. Constraints given from practical blending rules are also introduced in the optimization. Discrete values of ply thicknesses is a requirement. An ad-hoc discrete optimization strategy is developed, which enables to handle discrete variables

Analysis of the Effects of 3DP Parameters on Part Feature Dimensional Accuracy

3D printing (3DP) is a widely investigated scaffold manufacturing process for Tissue Engineering (TE). Useful scaffold geometries should have high porosity (60-80%) with small (100-500 μm) interconnected pores. Therefore dimensional accuracy on the micron level is one of the crucial parameters of the bone scaffolds. Previously it was shown that the behavior of scaffold geometries can be well simulated with Finite Element Modeling (FEM) however the prediction of actual strength and stiffness values are dependent on dimensional accuracy. This accuracy is in turn dependent on several parameters including particle size and shape, powderbinder interaction, and machine setup. In this work different scaffold strut sizes (0.3 - 0.5 mm) have been fabricated using two different plaster powders (zp102 and zp130) with variations in shell saturation levels, part print position, and part print orientation. The parameters for each powder were analyzed using a full 35 factorial experimental design. It was found that the part size and orientation had a significant effect on the dimensional accuracy while the influence of the shell saturation and position was relatively small. The results allow for better dimensional specification for scaffold geometry fabrication by defining the process parameters in 3DP that may be used further in scaffold accuracy optimization.Mechanical Engineerin