Evolutionary algorithms for synthesis and optimisation of sequential logic circuits

Considerable progress has been made recently 1n the understanding of combinational logic optimization. Consequently a large number of university and industrial Electric Computing Aided Design (ECAD) programs are now available for optimal logic synthesis of combinational circuits. The progress with sequential logic synthesis and optimization, on the other hand, is considerably less mature. In recent years, evolutionary algorithms have been found to be remarkably effective way of using computers for solving difficult problems. This thesis is, in large part, a concentrated effort to apply this philosophy to the synthesis and optimization of sequential circuits. A state assignment based on the use of a Genetic Algorithm (GA) for the optimal synthesis of sequential circuits is presented. The state assignment determines the structure of the sequential circuit realizing the state machine and therefore its area and performances. The synthesis based on the GA approach produced designs with the smallest area to date. Test results on standard fmite state machine (FS:M) benchmarks show that the GA could generate state assignments, which required on average 15.44% fewer gates and 13.47% fewer literals compared with alternative techniques. Hardware evolution is performed through a succeSSlOn of changes/reconfigurations of elementary components, inter-connectivity and selection of the fittest configurations until the target functionality is reached. The thesis presents new approaches, which combine both genetic algorithm for state assignment and extrinsic Evolvable Hardware (EHW) to design sequential logic circuits. The implemented evolutionary algorithms are able to design logic circuits with size and complexity, which have not been demonstrated in published work. There are still plenty of opportunities to develop this new line of research for the synthesis, optimization and test of novel digital, analogue and mixed circuits. This should lead to a new generation of Electronic Design Automation tools.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Evolutionary algorithms for synthesis and optimisation of sequential logic circuits.

Considerable progress has been made recently 1n the understanding ofcombinational logic optimization. Consequently a large number of universityand industrial Electric Computing Aided Design (ECAD) programs are nowavailable for optimal logic synthesis of combinational circuits. The progresswith sequential logic synthesis and optimization, on the other hand, isconsiderably less mature.In recent years, evolutionary algorithms have been found to be remarkablyeffective way of using computers for solving difficult problems. This thesis is,in large part, a concentrated effort to apply this philosophy to the synthesisand optimization of sequential circuits.A state assignment based on the use of a Genetic Algorithm (GA) for theoptimal synthesis of sequential circuits is presented. The state assignmentdetermines the structure of the sequential circuit realizing the state machineand therefore its area and performances. The synthesis based on the GAapproach produced designs with the smallest area to date. Test results onstandard fmite state machine (FS:M) benchmarks show that the GA couldgenerate state assignments, which required on average 15.44% fewer gatesand 13.47% fewer literals compared with alternative techniques.Hardware evolution is performed through a succeSSlOn ofchanges/reconfigurations of elementary components, inter-connectivity andselection of the fittest configurations until the target functionality is reached.The thesis presents new approaches, which combine both genetic algorithmfor state assignment and extrinsic Evolvable Hardware (EHW) to designsequential logic circuits. The implemented evolutionary algorithms are able todesign logic circuits with size and complexity, which have not beendemonstrated in published work.There are still plenty of opportunities to develop this new line of research forthe synthesis, optimization and test of novel digital, analogue and mixedcircuits. This should lead to a new generation of Electronic DesignAutomation tools

Evolutionary algorithms for synthesis and optimization of sequential logic circuits

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MODELLING AND STABILITY ANALYSIS OF ELECTRO-MECHANICAL ACTUATION SYSTEM FOR MORE-ELECTRIC AIRCRAFT

In modern electric aircraft, many conventional systems are replaced with their electrical equivalents. Actuation system is one system that is replaced by electromechanical actuators instead of hydraulic actuators. Electromechanical actuators are powered by electrical motor through a set of power electronic conversion interfaces. The actuator’s main role is to provide actuation for flight control surfaces, which is subject to aerodynamic loads. The aerodynamic load along with the actuator dynamics have certain characteristics that could interact with the power system. This is because, in case of interactions, the overall system might destabilise but both electrical and mechanical components can wear down. In this project, electromechanical interaction in the rudder electromechanical actuation system is investigated. Full model of the actuator is tested that highlights dynamics of which some are critical. Simplified models are suggested in attempt to include only the crucial actuator dynamics and neglect the unimportant ones. The proposed models show good matching with the full detailed model. Origin of anti-resonance is investigated due to its effect on system stability. It is shown that for closed speed loop and closed position loop, anti-resonance occurs due to different factors. To make sure that the suggested modelling methodology is generic, rudder actuation system is sized for a range of aircraft sizes. Using small signal sensitivity, interaction is proved to occur between electrical and mechanical systems. A test rig is used to emulate the actuation system using Hardware In the Loop technique. The experimental rig reproduces the actuation system behaviour and validates the simulated work. Understanding of electromechanical interactions and their effects on the system stability will create opportunities to enhance the robustness of more electrical aircraft power system through improved design and/or control