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    SubjectsModel reference control (4)Airport ground movement (3)Airport Operations (3)Aircraft propulsion (2)Airport operations (2)View MoreJournalEnergies (3)Engineering Applications of Artificial Intelligence (2)IEEE Transactions on Intelligent Transportation Systems (2)International Journal of Systems Science (2)Nuclear Engineering and Design (2)View MoreAuthors
    Stewart, Paul (35)
    Stewart, Paul (33) ccChen, Jun (8)Chen, Jun (7) ccBingham, Chris (6)View MoreYear (Issue Date)2015-09-15 (2)2016-10-31 (2)2018-11-03 (2)2001-11 (1)2002-12-10 (1)View MoreTypesArticle (32)Edited Journal (1)Edited journal (1)Meetings and Proceedings (1)

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    Module layout optimization using a genetic algorithm in light water modular nuclear reactor power plants.

    Wrigley, P.A.; Wood, P.; Stewart, Paul; Robertson, D. (Elsevier, 2018-11-03)
    The Small Modular Reactor (SMR) concept is designed such that it will solve some of the construction problems of large reactors. SMRs are designed to be “shop fabricated and then transported as modules to the sites for installation” (IAEA, 2018). As a consequence they theoretically have shorter build schedules and require less capitalinvestment(Locatelli etal.,2014).Factory builtmodulescanalsoincreasesafetyandproductivity, dueto higher quality tools and inspection available. A literature review has highlighted substantial work has been undertaken in the research, development and construction of different types of reactors and reactor modules but the design of balance of plant modules has not been extensively researched (Wrigley et al., 2018). The focus of this paperis a casestudy for balanceofplant modulesin alightwaterreactorwhich alsocould haveapplications to other reactor types. Modules thataredesignedfor factorybuildandtransport maybebuiltinastandardized moduleapproach.By maximizing module size for transport, this maximizes work offsite, to achieve the cost and schedule savings associated. A design method needs to be developed to help support this approach. To enable this, a three step method is proposed: group components into modules, layout the modules and arrange components inside the modules. The Shearon Harris nuclear power plant was chosen for its publically available data. A previous study on this plant used matrix reordering techniques to group components and heuristically assign them to large modules, built for construction in an assembly area on site, highlighting a potential capital cost savings of 15%. This paper utilizes the same allocation of components to modules as the previous study but aims to undertake the challenge of how balance of plant modules should be arranged. The literature review highlighted that although the facility and plant layout problem has been extensively researched, mathematical layout optimization has not been applied to nuclear power plants. Many techniques for layout optimization have been developed for facilities and process plants however. The work in this paper develops an optimization model using a genetic algorithm for module layout and allocation within a nuclear power plant. This paper analysed two configurations of modules, where balance of plant modules are located on either one or two sides of the nuclear island. The objective function was to minimise pipe length. In the original research, where the plant was configured for assembly on site, the balance of plant modules are located around three sides of the nuclear island. The objective function was calculated at 14,914. As the distances are calculated rectilinearly, this number would be higher in reality as pipework has to be routed around containment. The optimization reduced the objective function by 33.9% and 37.8% for the three and four floor layouts respectively when balance of plant modules are located on two sides of the nuclear island. Furthermore, when modules are located on one side of the nuclear island, the objective function was reduced by 45.4% and 46.1% for three and four floor layouts respectively. This will reduce materials used, reduce build time and hence reduce the cost of a nuclear power plant. This method will also save design time when developing the layout of modules around the plant.
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    Design of robust fuzzy-logic control systems by multi-objective evolutionary methods with hardware in the loop.

    Stewart, Paul; Stone, David; Fleming, Peter (Elsevier, 2004-05-10)
    Evolutionary development of a fuzzy-logic controller is described and is evaluated in the context of hardware in the loop. It had been found previously that a robust speed controller could be designed for a DC motor motion control platform via off-line fuzzy logic controller design. However to achieve the desired performance, the controller required manual tuning on-line. This paper investigates the automatic design of a fuzzy logic controller directly onto hardware. An optimiser which modifies the fuzzy membership functions, rule base and defuzzification algorithms is considered. A multi-objective evolutionary algorithm is applied to the task of controller development, while an objective function ranks the system response to find the Pareto-optimal set of controllers. Disturbances are introduced during each evaluation at run-time in order to produce robust performance. The performance of the controller is compared experimentally with the fuzzy logic controller which has been designed off-line, and a standard PID controller which has been tuned online. The on-line optimised fuzzy controller is shown to be robust, possessing excellent steady-state and dynamic characteristics, demonstrating the performance possibilities of this type of approach to controller design.
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    Energy harvesting and power network architectures for the multibody advanced airship for transport high altitude cruiser-feeder airship concept

    Smith, Tim; Bingham, Chris; Stewart, Paul; Allarton, R.; Stewart, Jill (Institution of Mechanical Engineers, 2013-01-09)
    This article presents results of preliminary investigations in the development of a new class of airship. Specific focus is given to photo-electric harvesting as a primary energy source, power architectures and energy audits for life support, propulsion and ancillary loads to support the continuous daily operation of the primary airship (cruiser) at stratospheric altitudes (similar to 15 km). The results are being used to drive the requirements of the FP7 multibody advanced airship for transport programme, which is to globally transport both passengers and freight using a 'feeder-cruiser' concept. It is shown that there is a potential trade off to traditional cost and size limits and, although potentially very complex, a first-order approximation is used to demonstrate sensitivities to the economics of the lifting gas. This presented concept is substantially different to those of conventional aircraft due to the airship size and the inherent requirement to harvest and store sufficient energy during 'daylight' operation to guarantee safe operation during 'dark hours'. This is particularly apparent when the sizing of the proposed electrolyser is considered, as its size and mass increases nonlinearly with decreasing daylight duty. The study also considers the integration of photovoltaics with various electrical architectures, in safety critical environments. A mass audit is also included that shows that if the electrolyser was omitted in such systems, the overall impact will be small compared to structural and propulsion masses. It should be noted that although the technology bias is application specific, the underlying principles are much widely applicable to other energy harvesting and power management sectors.
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    Comparison of two novel MRAS based strategies for identifying parameters in permanent magnet synchronous motors.

    Liu, Kan; Zhang, Qiao; Zhu, Zi-Qiang; Zhang, Jing; Shen, An-Wen; Stewart, Paul (Springer., 2010-11-11)
    Two Model Reference Adaptive System (MRAS) estimators are developed for identifying the parameters of permanent magnet synchronous motors (PMSM) based on Lyapunov stability theorem and Popov stability criterion, respectively. The proposed estimators only need online detection of currents, voltages and rotor rotation speed, and are effective in the estimation of stator resistance, inductance and rotor flux-linkage simultaneously. Their performances are compared and verified through simulations and experiments. It shows that the two estimators are simple and have good robustness against parameter variation and are accurate in parameter tracking. However, the estimator based on Popov stability criterion, which can overcome the parameter variation in a practical system, is superior in terms of response speed and convergence speed since there are both proportional and integral units in the estimator in contrast to only one integral unit in the estimator based on Lyapunov stability theorem. In addition, there is no need of the expert experience which is required in designing a Lyapunov function
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    Preference-based evolutionary algorithm for airport surface operations.

    Weiszer, Michal; Chen, Jun; Stewart, Paul; Zhang, Xuejun (Elsevier, 2018-04-21)
    In addition to time efficiency, minimisation of fuel consumption and related emissions has started to be considered by research on optimisation of airport surface operations as more airports face severe congestion and tightening environmental regulations. Objectives are related to economic cost which can be used as preferences to search for a region of cost efficient and Pareto optimal solutions. A multi-objective evolutionary optimisation framework with preferences is proposed in this paper to solve a complex optimisation problem integrating runway scheduling and airport ground movement problem. The evolutionary search algorithm uses modified crowding distance in the replacement procedure to take into account cost of delay and fuel price. Furthermore, uncertainty inherent in prices is reflected by expressing preferences as an interval. Preference information is used to control the extent of region of interest, which has a beneficial effect on algorithm performance. As a result, the search algorithm can achieve faster convergence and potentially better solutions. A filtering procedure is further proposed to select an evenly distributed subset of Pareto optimal solutions in order to reduce its size and help the decision maker. The computational results with data from major international hub airports show the efficiency of the proposed approach.
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    A new aircraft architecture based on the ACHEON Coanda effect nozzle: flight model and energy evaluation

    Marques, Jose Pascoa; Porreca, Eliana; Smith, Tim; Stewart, Paul; Subhash, Maharshi; Sunol, Anna; Vucinic, Dean; Trancossi, Michele; Madonia, Mauro; Dumas, Antonio; et al. (Springer, 2016-03-12)
    Aeronautic transport has an effective necessity of reducing fuel consumption and emissions to deliver efficiency and competitiveness driven by today commercial and legislative requirements. Actual aircraft configurations scenario allows envisaging the signs of a diffused technological maturity and they seem very near their limits. This scenario clearly shows the necessity of radical innovations with particular reference to propulsion systems and to aircraftarchitecture consequently. Methods This paper presents analyses and discusses a promising propulsive architecture based on an innovative nozzle, which allows realizing the selective adhesion of two impinging streams to two facing jets to two facing Coanda surfaces. This propulsion system is known with the acronym ACHEON (Aerial Coanda High Efficiency Orienting Nozzle). This paper investigates how the application of an all-electric ACHEONs propulsion system to a very traditional commuter aircraft can improve its relevant performances. This paper considers the constraints imposed by current state-of-the-art electric motors, drives, storage and conversion systems in terms of both power/energy density and performance and considers two different aircraft configurations: one using battery only and one adopting a more sophisticated hybrid cogeneration. The necessity of producing a very solid analysis has forced to limit the deflection of the jet in a very conservative range (±15°) with respect to the horizontal. This range can be surely produced also by not optimal configurations and allow minimizing the use of DBD. From the study of general flight dynamics equations of the aircraft in two-dimensional form it has been possible to determine with a high level of accuracy the advantages that ACHEON brings in terms of reduced stall speed and of reduced take-off and landing distances. Additionally, it includes an effective energy analysis focusing on the efficiency and environmental advantages of the electric ACHEON based propulsion by assuming the today industrial grade high capacity batteries with a power density of 207 Wh/kg. Results It has been clearly demonstrated that a short flight could be possible adopting battery energy storage, and longer duration could be possible by adopting a more sophisticated cogeneration system, which is based on cogeneration from a well-known turboprop, which is mostly used in helicopter propulsion. This electric generation system can be empowered by recovering the heat and using it to increase the temperature of the jet. It is possible to transfer this considerable amount of heat to the jet by convection and direct fluid mixing. In this way, it is possible to increase the energy of the jets of an amount that allows more than recover the pressure losses in the straitening section. In this case, it is then possible to demonstrate an adequate autonomy of flight and operative range of the aircraft. The proposed architecture, which is within the limits of the most conservative results obtained, demonstrates significant additional benefits for aircraft manoeuvrability. In conclusion, this paper has presented the implantation of ACHEON on well-known traditional aircraft, verifying the suitability and effectiveness of the proposed system both in terms of endurance with a cogeneration architecture and in terms of manoeuvrability. It has demonstrated the potential of the system in terms of both takeoff and landing space requirements. Conclusions This innovation opens interesting perspectives for the future implementation of this new vector and thrust propulsion system, especially in the area of greening the aeronautic sector. It has also demonstrated that ACHEON has the potential of renovating completely a classic old aircraft configuration such as the one of Cessna 402.
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    Torque maximisation of the Pmac motor for high performance, low inertia operation

    Stewart, Paul (Wiley, 2008-10-22)
    This paper describes the techniques applied to maximise the torque envelope of the permanent magnet AC (PMAC) motor operating under current and voltage constraints. Standard steady-state descriptions of the system are often suitable for control purposes when the rotor velocity is varying relatively slowly. In low inertia applications such as clutchless gearchange operations, where in the pursuit of driveability, the motor is required to accelerate and decelerate its own rotor inertia as quickly as possible. In this case, the voltage drop due to the current dynamics start to become significant. This paper presents a method to reserve voltage headroom dynamically in the field-weakening region in order to maximise the torque envelope when the effective inertia is low. Experimental results show the effectiveness of this approach.
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    Commutation of permanent-magnet synchronous AC motors for military and traction applications

    Stewart, Paul; Kadirkamanathan, Visakan (Institute of Electrical and Electronic Engineers, 2003-06-05)
    The permanent-magnet ac (PMAC) motor requires accurate position information to be supplied to the controller so that the applied currents can be modulated in synchronism with the rotor. In the flux-weakening region of operation, accurate rotor position information is critical to control the relative phase of the applied stator voltages. The design of controllers, which can operate without direct position feedback, have been the subject of intense development. The most commonly cited justifications for the elimination of the absolute position encoder are those of cost, and the reduction of the overall dimensions of the motor. However, certain military specifications apply stringent constraints to the use of both sensors and estimation techniques. Absolute encoders are frequently prohibited for applications such as tank turret drives due to their relatively fragile nature. Fully sensorless operation has been the focus of development for all classes of electric motors, but again is precluded not only in certain military applications, but also in traction applications for a number of manufacturers.
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    Advances in control engineering

    Stewart, Paul (Multidisciplinary Digital Publishing Institute (MDPI), 2015-06-30)
    The last twenty years have seen a radical step-change in the capability and application of Control Engineering, brought about by advances in computational speed and capacity. Control design for contemporary, complex engineering systems has developed alongside Computer Aided Control System Design, powerful real-time embedded computation, and both off-line and on-line optimization techniques. This Special Issue will bring together papers, which particularly describe recent advances in Control Engineering in industrial applications and complex engineering systems, describing the application of novel theory across all areas of Automation. Papers which include practical experimental results are particularly encouraged, as are papers which set Control advances in the wider context of, for example, society, economics, energy and environment.
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    Electrical power and energy systems for transportation applications

    Stewart, Paul; Bingham, Chris (Multidisciplinary Digital Publishing Institute (MDPI), 2016-07-14)
    This book contains the successful invited submissions [1-25] to a Special Issue of Energies on the subject area of “Electrical Power and Energy Systems for Transportation Applications�.
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