8 research outputs found
Robust frequency regulation in mobile microgrids: HIL implementation
© 2007-2012 IEEE. It is undeniable that marine vessel systems play an important role to transfer huge loads and weapons with low cost. However, ship power systems produce a lot of greenhouse gases, which in turn lead to serious environmental pollution. Hence, the utilizing of wind turbines (WTs), solar generation, sea wave energy (SWE), and energy storage systems (ESSs) in marine vessel power systems have been attracting a lot of attention in recent years. In this paper, it is assumed that a marine vessel power system with photovoltaic (PV), WT, SWE, and ESS can be regarded as a mobile-islanded MG. Then, a novel topology for hybrid shipboard microgrids (MGs) is presented. Next, in order to make a balance between consumption and power generation in shipboard MGs, an optimal modified model-free nonlinear sliding mode controller is introduced for the secondary load frequency control. Since the quality of the control actions of the proposed model-free approach depends on its parameters, a hybrid version of the sine-cosine algorithm (SCA) and wavelet-mutation (WM), called SCAWM, is employed to find the best value of these coefficients. Comparisons are conducted with other existing methodologies, such as model predictive control, interval type-2 fuzzy logic controller, and conventional PI (PI) to establish the supremacy of the newly suggested control strategy. Finally, a real-time hardware-in-the-loop (HIL) simulation based on OPAL-RT is accomplished to affirm the applicability of the suggested controller, from a systemic perspective, for the load frequency control problem in the shipboard MG
Contribution of ion emission to sputtering of uranium dioxide by highly charged ions
Measurements of the cluster size (n) distribution of secondary
(UO ions from sputtering of uranium dioxide (UO by
Ne8+, Ar8+ and Xe ions (q=10, 23) at fixed kinetic energy
(81 keV) have been performed with a time-of-flight mass spectrometer. The
cluster ion yields Y follow a power law with
. This is in contrast to a statistical recombination
of the constituents upon ejection, but in agreement with the predictions of
collective ejection models. Such a power law was also observed in the
electronic stopping regime with MeV/u ions. The exponent is found
to decrease with increasing projectile mass (and thus total sputter yield)
at fixed kinetic energy. The ratio of emitted ionic clusters to monomers
varies from 3 to 4.5 depending on the projectile. The contribution of
positive ions to the total sputtering yield amounts to about 0.03%
A Framework for Evaluating Schedulability Analysis Tools
International audienceThere exists a large variety of schedulability analysis tools based on dierent, often incomparable timing models. This variety makes it dicult to choose the best t for analyzing a given real-time system. To help the research community to better evaluate analysis tools and their underlying methods, we are developing a framework which consists of (1) a simple language called RTSpec for specifying real-time systems, (2) a tool chain which translates a system specication in RTSpec into an input for various analysis tools, and (3) a set of benchmarks. Our goal is to enable users and developers of schedulability analysis tools to compare such tools systematically, automatically and rigorously