1,720,970 research outputs found
Aggregation-based model reduction for tokamak control
No full textThe use of model reduction schemes based on eigenstructure analysis is shown to be useful in the study of control problems in tokamak experiments. In particular, state aggregation techniques allow to produce reduced-order models where the physical meaning of the state variables is preserved. This turns out to be useful to obtain interesting interpretations in terms of physical quantities of the simplified model, its parameters, and the approximations involve
Model reduction techniques in tokamak modelling
No full textIn present tokamak experiments, there is the need of sufficiently detailed models describing the plasma behaviour and its electromagnetic coupling with the active and metallic structures for simulation and control design. The required level of detail yields linearized model of the system at particular working points of very high order, thus complicating the design of controllers of the position and shape of the plasma. In this paper, several model reduction techniques which are available from linear state-space control theory are considered with application to tokamak modelling. In particular, a technique based on selective modal analysis is proposed, and its effectiveness in approximating the overall system behaviour while retaining the physical meaning of the state variables is show
Active Contours Approach for Plasma Boundary Reconstruction
No full textIn the current generation of tokamak devices, fusion performance is related to plasma geometric characteristics as elongation and triangularity. Shape diagnostics and control systems are, therefore, essential to plasma operations. It follows that the quality of a tokamak control system depends on the availability of fast and reliable measurements of plasma position and shape. For this purpose, classic reconstruction and control algorithms that have been applied to existing machines refer to the position of a discrete set of points (gaps) around the outermost flux surface. The paper presents an attempt of producing an integral, more than pointwise description of the plasma boundary using modern techniques, derived from the active vision field. It provides an intuitive and elegant tool for plasma boundary representation and dynamic reconstruction, while widening the point of view over plasma shape diagnostics and control systems. A comparison with the reconstruction code currently available at JET will be presented
Virtual mechanical load setup for steer-by-wire: a case study
No full textIn the electric drives scenario, the automotive is one of the most active and promising application fields. So far, electric steer eliminated many elements of a hydraulic system, with fair fuel economy in the process. The next step, the electronic steering, is in progress. It will definitively substitute any mechanical connection with the steering wheel by wire-transmitted digital signals to one or more remote electric motors. Obviously, the design of any control strategy has to pass through hardware verification. At the early stages, or when a real car prototype is not easily available, the design could greatly benefit of a hardware-in-the-loop (HIL) emulator, to enable the fast control prototyping. In the paper, a reduced-order model, implemented with a high-dynamic electric drive, substitutes the real mechanical load. The model details, the system architecture and the experimental results are presented in the paper
Non linear model of the gas introduction module for plasma density control at JET
No full textThe gas introduction module (GIM) is the basic system used in Joint European Torus (JET) to provide the vacuum vessel with the amount of gas necessary for a successful plasma discharge. The plasma density feedback (PDF) system controls the GIM piezo-electric valve allowing the desired amount of gas to flow in the vacuum vessel. The unavailability of a flow measurement is the main reason for the development of an accurate flow model, able to predict and calculate the number of particles flowing within an acceptable error margin. This paper describes a GIM model that uses the control signal of the piezo-electric valve to compute the pressure evolution inside the GIM reservoir and, using the pressure estimation, obtains the particles flow considering also the dynamic heat exchange effect between the gas and the structure of the GIM
- …
