Geometric guides for interactive evolutionary design

This thesis describes the addition of novel Geometric Guides to a generative Computer-Aided Design (CAD) application that supports early-stage concept generation. The application generates and evolves abstract 3D shapes, used to inspire the form of new product concepts. It was previously a conventional Interactive Evolutionary system where users selected shapes from evolving populations. However, design industry users wanted more control over the shapes, for example by allowing the system to influence the proportions of evolving forms. The solution researched, developed, integrated and tested is a more cooperative human-machine system combining classic user interaction with innovative geometric analysis. In the literature review, different types of Interactive Evolutionary Computation (IEC), Pose Normalisation (PN), Shape Comparison, and Minimum-Volume Bounding Box approaches are compared, with some of these technologies identified as applicable for this research. Using its Application Programming Interface, add-ins for the Siemens NX CAD system have been developed and integrated with an existing Interactive Evolutionary CAD system. These add-ins allow users to create a Geometric Guide (GG) at the start of a shape exploration session. Before evolving shapes can be compared with the GG, they must be aligned and scaled (known as Pose Normalisation in the literature). Computationally-efficient PN has been achieved using geometric functions such as Bounding Box for translation and scaling, and Principle Axes for the orientation. A shape comparison algorithm has been developed that is based on the principle of non-intersecting volumes. This algorithm is also implemented with standard, readily available geometric functions, is conceptually simple, accessible to other researchers and also offers appropriate efficacy. Objective geometric testing showed that the PN and Shape Comparison methods developed are suitable for this guiding application and can be efficiently adapted to enhance an Interactive Evolutionary Design system. System performance with different population sizes was examined to indicate how best to use the new guiding capabilities to assist users in evolutionary shape searching. This was backed up by participant testing research into two user interaction strategies. A Large Background Population (LBP) approach where the GG is used to select a sub-set of shapes to show to the user was shown to be the most effective. The inclusion of Geometric Guides has taken the research from the existing aesthetic focused tool to a system capable of application to a wider range of engineering design problems. This system supports earlier design processes and ideation in conceptual design and allows a designer to experiment with ideas freely to interactively explore populations of evolving solutions. The design approach has been further improved, and expanded beyond the previous quite limited scope of form exploration

STRUCTURAL CONTROL OF OFFSHORE WIND TURBINES USING PASSIVE AND SEMI-ACTIVE CONTROL

Offshore wind energy has the potential to generate substantial electricity production compared to onshore locations, due to the high-quality wind resource. Offshore wind turbines must endure severe offshore environmental conditions and be cost effective, in order to be sustainable. As a result, load mitigation becomes crucial in successfully enabling deployment of offshore wind turbines. A direct approach to reduce loads in offshore wind turbines is the application of structural control techniques. So far, the application of structural control techniques to offshore wind turbines has shown to be effective in reducing fatigue and extreme loads of turbine structures. However, the majority of previous research regarding the application of structural control to offshore wind turbine noted the needs for the high-fidelity analysis for structural control using a computer aided engineering (CAE) tool, such as FASTv8. In this dissertation, a structural control module coupled with FASTv8 is developed to meet the needs for high-fidelity analysis of structural control techniques for various OWTs. In addition, the developed control module is updated to analyze various structural control devices operating both passively and semi-actively. The dynamics of an omni-directional pendulum-type tuned mass damper and orthogonal tuned liquid column dampers (TLCDs) are mathematically modeled and incorporated into the structural control module. With the developed control module, several structural control devices are optimized through a variety of techniques (parametric study, exhaustive search and multi-objective optimization). Solving optimization problems not only provides the parameters for each control device that can be applicable to other multi-megawatts offshore wind turbines, but also provides insight into the effects of design variables on the control performance. Site-specific meteorological and oceanographic data that consists of a combination of wind and wave data are processed and compiled in order to establish key design load cases. With the optimal designs of structural control devices, non-linear fully-coupled time marching simulations are conducted by running a series of design load cases in order to investigate the impacts of passive and semi-active structural control on improving fatigue and extreme behaviors of fixed-bottom and floating offshore wind turbines. The simulation results demonstrate the effectiveness of various structural control techniques on reducing fatigue and extreme loadings

Fatigue Analysis and Testing of Wind Turbine Blades

This thesis focuses on fatigue analysis and testing of large, multi MW wind turbine blades. The blades are one of the most expensive components of a wind turbine, and their mass has cost implications for the hub, nacelle, tower and foundations of the turbine so it is important that they are not unnecessarily strong. Fatigue is often an important design driver, but fatigue of composites is poorly understood and so large safety factors are often applied to the loads. This has implications for the weight of the blade. Full scale fatigue testing of blades is required by the design standards, and provides manufacturers with confidence that the blade will be able to survive its service life. This testing is usually performed by resonating the blade in the flapwise and edgewise directions separately, but in service these two loads occur at the same time. A fatigue testing method developed at Narec (the National Renewable Energy Centre) in the UK in which the flapwise and edgewise directions are excited simultaneously has been evaluated by comparing the Palmgren-Miner damage sum around the blade cross section after testing with the damage distribution caused by the service life. A method to obtain the resonant test configuration that will result in the optimum mode shapes for the flapwise and edgewise directions was then developed, and simulation software was designed to allow the blade test to be simulated so that realistic comparisons between the damage distributions after different test types could be obtained. During the course of this work the shortcomings with conventional fatigue analysis methods became apparent, and a novel method of fatigue analysis based on multi-continuum theory and the kinetic theory of fracture was developed. This method was benchmarked using physical test data from the OPTIDAT database and was applied to the analysis of a complete blade. A full scale fatigue test method based on this new analysis approach is also discussed

Dynamically adjusting game-play in 2D platformers using procedural level generation

The rapid growth of the entertainment industry has presented the requirement for more efficient development of computerized games. Importantly, the diversity of audiences that participate in playing games has called for the development of new technologies that allow games to address users with differing levels of skills and preferences. This research presents a systematic study that explored the concept of dynamic difficulty using procedural level generation with interactive evolutionary computation. Additionally, the design, development and trial of computerized agents the play game levels in the place of a human player is detailed. The work presented in this thesis provides a solution to the rapid growth of the entertainment industry whilst providing a more effective means for developing computerized games

Nuclear Power

The world of the twenty first century is an energy consuming society. Due to increasing population and living standards, each year the world requires more energy and new efficient systems for delivering it. Furthermore, the new systems must be inherently safe and environmentally benign. These realities of today's world are among the reasons that lead to serious interest in deploying nuclear power as a sustainable energy source. Today's nuclear reactors are safe and highly efficient energy systems that offer electricity and a multitude of co-generation energy products ranging from potable water to heat for industrial applications. The goal of the book is to show the current state-of-the-art in the covered technical areas as well as to demonstrate how general engineering principles and methods can be applied to nuclear power systems

Evolutionary Computation

This book presents several recent advances on Evolutionary Computation, specially evolution-based optimization methods and hybrid algorithms for several applications, from optimization and learning to pattern recognition and bioinformatics. This book also presents new algorithms based on several analogies and metafores, where one of them is based on philosophy, specifically on the philosophy of praxis and dialectics. In this book it is also presented interesting applications on bioinformatics, specially the use of particle swarms to discover gene expression patterns in DNA microarrays. Therefore, this book features representative work on the field of evolutionary computation and applied sciences. The intended audience is graduate, undergraduate, researchers, and anyone who wishes to become familiar with the latest research work on this field

Design of an optimal pendulum-tuned mass damper applied to offshore wind turbines

Tese (doutorado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2020.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).Offshore Wind Turbines (OWT) may experience excessive vibration levels caused by the actions of wind, waves, rotor torque, and seismic loads. To suppress the vibrations of these primary structures, the Tuned Mass Damper (TMD) is a widely used passive control alternative. Briefly, it is a damper that transfers the kinetic energy from the main structure to a secondary mass usually attached to the hub. These devices need to be finely tuned with a target self-vibration mode of the primary structure to work as dampers, otherwise, they could amplify structural vibrations. This thesis presents optimal parameters of a Pendulum-TMD (PTMD) to mitigates structural vibrations of OWTs levels. The PTMD is examined on a National Renewable Energy Lab (NREL) monopile 5 MW baseline wind turbine model using analytical and numerical procedures, such as a 2-degree-of-freedom (2DOF), spectral elements (SEM), and finite elements (FEM). Following design standards of OWTs structures wind and wave spectra computation, as well as the evaluation of the hydrodynamic and aerodynamic loads by computing the resultant peak displacement response at the OWT hub by a Power Spectral Density (PSD) analysis. In the validation of the OWT models, a result comparison is made with the NREL OpenFAST, finding good matching between the results. An in-house built Genetic Algorithm (GA) toolbox, coded in MATLAB® , is used then to optimally design parameters of a PTMD attached to the OWT. The chosen GA fitness function targets a minimization of the peak responses. The design parameters of the PTMD are the flexural rigidity and damping, the mass ratio, and the pendulum length

An Update on Power Quality

Power quality is an important measure of fitness of electricity networks. With increasing renewable energy generations and usage of power electronics converters, it is important to investigate how these developments will have an impact to existing and future electricity networks. This book hence provides readers with an update of power quality issues in all sections of the network, namely, generation, transmission, distribution and end user, and discusses some practical solutions

Benchmarking a wide spectrum of metaheuristic techniques for the radio network design problem

The radio network design (RND) is an NP-hard optimization problem which consists of the maximization of the coverage of a given area while minimizing the base station deployment. Solving RND problems efficiently is relevant to many fields of application and has a direct impact in the engineering, telecommunication, scientific, and industrial areas. Numerous works can be found in the literature dealing with the RND problem, although they all suffer from the same shortfall: a noncomparable efficiency. Therefore, the aim of this paper is twofold: first, to offer a reliable RND comparison base reference in order to cover a wide algorithmic spectrum, and, second, to offer a comprehensible insight into accurate comparisons of efficiency, reliability, and swiftness of the different techniques applied to solve the RND problem. In order to achieve the first aim we propose a canonical RND problem formulation driven by two main directives: technology independence and a normalized comparison criterion. Following this, we have included an exhaustive behavior comparison between 14 different techniques. Finally, this paper indicates algorithmic trends and different patterns that can be observed through this analysis.Publicad