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Now showing 1 - 5 of 5
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    How Price-Based Frequency Regulation Impacts Stability in Power Grids: A Complex Network Perspective
    (London : Hindawi, 2020) Ji, Peng; Zhu, Lipeng; Lu, Chao; Lin, Wei; Kurths, Jürgen
    With the deregulation of modern power grids, electricity markets are playing a more and more important role in power grid operation and control. However, it is still questionable how the real-time electricity price-based operation affects power grid stability. From a complex network perspective, here we investigate the dynamical interactions between price-based frequency regulations and physical networks, which results in an interesting finding that a local minimum of network stability occurs when the response strength of generators/consumers to the varying price increases. A case study of the real world-based China Southern Power Grid demonstrates the finding and exhibits a feasible approach to network stability enhancement in smart grids. This also provides guidance for potential upgrade and expansion of the current power grids in a cleaner and safer way. © 2020 Peng Ji et al.
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    Special issue on conceptual structures
    (Dordrecht [u.a.] : Springer Science + Business Media B.V, 2022) Alam, Mehwish; Braun, Tanya; Endres, Dominik; Yun, Bruno
    [no abstract available]
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    Variable Step Mollifiers and Applications
    (Berlin ; Heidelberg : Springer, 2020) Hintermüller, Michael; Papafitsoros, Kostas; Rautenberg, Carlos N.
    We consider a mollifying operator with variable step that, in contrast to the standard mollification, is able to preserve the boundary values of functions. We prove boundedness of the operator in all basic Lebesgue, Sobolev and BV spaces as well as corresponding approximation results. The results are then applied to extend recently developed theory concerning the density of convex intersections. © 2020, The Author(s).
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    Fixed-Time Connectivity Preserving Tracking Consensus of Multiagent Systems with Disturbances
    (London : Hindawi, 2020) Sun, Fenglan; Liu, Peiyong; Kurths, Jürgen; Zhu, Wei
    This text studies the fixed-time tracking consensus for nonlinear multiagent systems with disturbances. To make the fixed-time tracking consensus, the distributed control protocol based on the integral sliding mode control is proposed; meanwhile, the adjacent followers can be maintained in a limited sensing range. By using the nonsmooth analysis method, sufficient conditions for the fixed-time consensus together with the upper and lower bounds of convergence time are obtained. An example is given to illustrate the potential correctness of the main results. © 2020 Fenglan Sun et al.
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    Revealing the co-action of viscous and multistability hysteresis in an adhesive, nominally flat punch: A combined numerical and experimental study
    ([Erscheinungsort nicht ermittelbar] : arXiv, 2022) Christian Müller, Manar Samri, René Hensel, Eduard Arzt, Martin H. Müser
    Viscoelasticity is well known to cause a significant hysteresis of crack closure and opening when an elastomer is brought in and out of contact with a flat, rigid counterface. In contrast, the idea that adhesive hysteresis can also result under quasi-static driving due to small-scale, elastic multistability is relatively new. Here, we study a system in which both mechanisms act concurrently. Specifically, we compare the simulated and experimentally measured time evolution of the interfacial force and the real contact area between a soft elastomer and a rigid, flat punch, to which small-scale, single-sinusoidal roughness is added. To this end, we further the Green's function molecular dynamics method and extend recently developed imaging techniques to elucidate the rate- and preload-dependence of the pull-off process. Our results reveal that hysteresis is much enhanced when the saddle points of the topography come into contact, which, however, is impeded by viscoelastic forces and may require sufficiently large preloads. A similar coaction of viscous- and multistability effects is expected to occur in macroscopic polymer contacts and be relevant, e.g., for pressure-sensitive adhesives and modern adhesive gripping devices.