1,720,986 research outputs found
Genetic algorithms in control systems engineering
No full textDevelopments in computational models of evolutionary processes have led to the realization of powerful, robust, and general optimization and adaptive systems collectively called evolutionary algorithms. In this paper, we consider one member of this class of algorithms, the genetic algorithm, and describe the features and characteristics that are particularly appropriate for applications in control systems engineering. The versatility and robust qualities of the algorithm are considered and a number of application areas described. Some prospective future directions are also identifie
Gas turbine engine controller design using multiobjective genetic algorithms
No full textThis paper describes the use of multiobjective genetic algorithms (MOGAs) in the design of a multivariable control system for a gas turbine engine. It is shown how the MOGA confers an immediate advantage over conventional multiobjective optimization methods by evolving a family of Pareto-optimal solutions allowing the control engineer to examine the trade-offs between the different design objectives. In addition, the paper demonstrates how the genetic algorithm can be used to search in both controller structure and parameter space thereby offering a potentially more general approach to optimization in controller design than traditional numerical methods
Transient wing in ground effect aerodynamics: comparisons of static and dynamic testing
No full textThe aerodynamic investigation of vehicles in wind tunnels has historically been performed via a series of time averaged measurements at fixed static attitude. However, due to their nature vehicles exploiting ground effect tend to be inherently dynamic and thus there is potential for improvement in the accuracy and predictive capability of wind tunnel testing. This paper describes a novel approach to testing that allows for an increase in fidelity by performing dynamic tests in the wind tunnel. This improved capability is then used to evaluate the transient aerodynamic behaviour of ac wing in ground effect. Results from wind tunnel tests of a single element GA(W)-1 wing in ground effect undergoing a heaving motion are compared to force values with the wing stationary at a number of positions
Framework for aircraft cost optimization using multidisciplinary analysis
No full textThis report summarizes the work that has been carried out as part of the Flapless Air Vehicle Integrated Industrial Research project, a five-year research program looking at technologies for future aircraft. A novel classification of aircraft product definition is used, and a framework to estimate the life cycle cost of aircraft using the product definition is presented. The acquisition costs are estimated using a hierarchical structure and a discrete-event simulation model is used to estimate the maintenance and operation costs. The cost models developed are integrated into the conceptual aircraft design process to facilitate the comparison between different configurations. The usage of the life cycle cost framework as a decision support tool is outlined by using the cost models to perform multidisciplinary analysis and optimization studies
Control mode analysis for advanced concept aero-engines
No full textThis paper describes a novel approach to the problem of control mode analysis for advanced concept gas turbine aero-engines. Using a multiobjective evolutionary algorithm, candidate control modes are selected and tested on models of the propulsion system to assess performance, safety, stability and other important design criteria. An example controller design problem, considering some of the problems likely to be associated with new variable cycle engine concepts, is presented to demonstrate how the proposed approach may be employed to examine many design objectives, from different disciplines, in parallel. Potential control schemes are evaluated and compared with one another within an optimization framework. This comparative analysis of different control modes may be used to make more informed decisions regarding the nature of the control to be employed, acceptable performance margins and elements of the engine design
Hybrid control using evolutionary tuned fuzzy controller techniques - a study
No full textMany real world systems exist that have operating regions or regimes that exhibit varying degrees of non-lineararity. An example of this are the significant variations in the dynamic characteristics of a distributed collector field within a solar power plant. Her a gain schedule controller using pole placement with feedforward was chosen to control the more linear operating regimes of the plant. Then a study was carried out to find the best suited and most efficient evolutionary-tuned fuzzy logic based controller, for rexlusive and concentrated use on the plant's more non-linear regions
Towards fuzzy gain scheduling for gas turbine aero-engine systems: A multiobjective approach
No full textThis paper investigates the use of a non-conventional approach to the control of a gas turbine aero-engine. The rationale behind this study is the need to develop advanced tools and techniques that can assist in improving the performances of the system and which simultaneously enhance the flexibility of the control strategy. Here, two such methods, fuzzy logic and evolutionary algorithms, are considered. Emerging from new requirements for gas turbine engine control, a flexible gain scheduler is developed and analyzed. A hierarchical multiobjective genetic algorithm is developed to perform search and optimization of the candidate fuzzy scheduling solutions.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Simulation based life cycle cost modelling as a decision support tool
No full textThis paper summarizes the work that has been carried out as part of the FLAVIIR project, a 5year research program looking at technologies for future unmanned air vehicles. This is a UKEPSRC funded project sponsored by BAE systems. A framework is presented in which a life cyclecost model can be integrated into the design process to facilitate the comparison between differentconfigurations. The architecture to estimate the life cycle cost and the associated models aredescribed. The acquisition costs are estimated using a hierarchical structure and a discretesimulation model is used to estimate the maintenance and operation costs. It is then demonstratedhow the framework can be used to evaluate the cost penalty of different design concepts
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