230,974 research outputs found
Automatic loop-shaping in quantitative feedback theory using genetic algorithms
Design automation in Quantitative Feedback Theory (QFT) is addressed in
this paper. An automatic loop shaping procedure based on Genetic Algorithms
(GAs) is developed, where a robust controller for uncertain plants can be designed
automatically such that the cost of feedback is minimised and all robust stability
and performance specifcations are satisfed. The developed approach can improve
the current QFT design in at least two aspects. One is in the design of an initial
controller for complicated plants, which might be difficult even to find a stabilising controller manually. The other is in improving the initial manual design by
optimisation of the performance index under the prescribed requirements within
the neighbourhood of the manual design. An illustrative example which compares
manual loop shaping with automatic loop shaping is presented
Evolutionary computation enabled game theory based modelling of electricity market behaviours and applications
The collapse of the Californian electricity market system in 2001 has highlighted urgency in research in intelligent electricity trading systems and strategies involving both suppliers and customs. In their trading systems, power generation companies under the new electricity trading arrangement (NETA) of the UK are now developing gaming strategies. However, modelling of such "intelligent" market behaviours is extremely challenging, because traditional mathematical and computer modelling techniques cannot cope with the involvement of game theory. In this paper, evolutionary computation enabled modelling of such system is presented. Both competitive and cooperative game theory strategies are taken into account in evolving the intelligent model. The model then leads to intelligent trading strategy development and decision support. Experimental tests, verification and validation are carried out with various strategies, using different model scales and data published by NETA. Results show that evolutionary computation enabled game theory involved modelling and decision making provides an effective tool for NETA trading analysis, prediction and support
Comparisons and Applications of Four Independent Numerical Approaches for Linear Gyrokinetic Drift Modes
To help reveal the complete picture of linear kinetic drift modes, four
independent numerical approaches, based on integral equation, Euler initial
value simulation, Euler matrix eigenvalue solution and Lagrangian particle
simulation, respectively, are used to solve the linear gyrokinetic
electrostatic drift modes equation in Z-pinch with slab simplification and in
tokamak with ballooning space coordinate. We identify that these approaches can
yield the same solution with the difference smaller than 1\%, and the
discrepancies mainly come from the numerical convergence, which is the first
detailed benchmark of four independent numerical approaches for gyrokinetic
linear drift modes. Using these approaches, we find that the entropy mode and
interchange mode are on the same branch in Z-pinch, and the entropy mode can
have both electron and ion branches. And, at strong gradient, more than one
eigenstate of the ion temperature gradient mode (ITG) can be unstable and the
most unstable one can be on non-ground eigenstates. The propagation of ITGs
from ion to electron diamagnetic direction at strong gradient is also observed,
which implies that the propagation direction is not a decisive criterion for
the experimental diagnosis of turbulent mode at the edge plasmas.Comment: 12 pages, 10 figures, accept by Physics of Plasma
Implantable RF-coiled chip packaging
In this paper, we present an embedded chip integration
technology that utilizes silicon housings and flexible
parylene radio frequency (RF) coils. As a demonstration
of this technology, a flexible parylene RF coil has been
integrated with an RF identification (RFID) chip. The coil
has an inductance of 16 ÎĽH, with two layers of metal
completely encapsulated in parylene-C. The functionality
of the embedded chip is verified using an RFID reader
module. Accelerated-lifetime soak testing has been
performed in saline, and the results show that the silicon
chip is well protected and the lifetime of our
parylene-encapsulated RF coil at 37 °C is more than 20
years
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