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End date: 2024 × Start date: 2020 × Subject: Electrical and electronic engineering ×

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Now showing 1 - 3 of 3
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    Tailoring electron beams with high-frequency self-assembled magnetic charged particle micro optics
    ([London] : Nature Publishing Group UK, 2022) Huber, R.; Kern, F.; Karnaushenko, D.D.; Eisner, E.; Lepucki, P.; Thampi, A.; Mirhajivarzaneh, A.; Becker, C.; Kang, T.; Baunack, S.; Büchner, B.; Karnaushenko, D.; Schmidt, O.G.; Lubk, A.
    Tunable electromagnets and corresponding devices, such as magnetic lenses or stigmators, are the backbone of high-energy charged particle optical instruments, such as electron microscopes, because they provide higher optical power, stability, and lower aberrations compared to their electric counterparts. However, electromagnets are typically macroscopic (super-)conducting coils, which cannot generate swiftly changing magnetic fields, require active cooling, and are structurally bulky, making them unsuitable for fast beam manipulation, multibeam instruments, and miniaturized applications. Here, we present an on-chip microsized magnetic charged particle optics realized via a self-assembling micro-origami process. These micro-electromagnets can generate alternating magnetic fields of about ±100 mT up to a hundred MHz, supplying sufficiently large optical power for a large number of charged particle optics applications. That particular includes fast spatiotemporal electron beam modulation such as electron beam deflection, focusing, and wave front shaping as required for stroboscopic imaging.
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    A new dimension for magnetosensitive e-skins: active matrix integrated micro-origami sensor arrays
    ([London] : Nature Publishing Group UK, 2022) Becker, Christian; Bao, Bin; Karnaushenko, Dmitriy D.; Bandari, Vineeth Kumar; Rivkin, Boris; Li, Zhe; Faghih, Maryam; Karnaushenko, Daniil; Schmidt, Oliver G.
    Magnetic sensors are widely used in our daily life for assessing the position and orientation of objects. Recently, the magnetic sensing modality has been introduced to electronic skins (e-skins), enabling remote perception of moving objects. However, the integration density of magnetic sensors is limited and the vector properties of the magnetic field cannot be fully explored since the sensors can only perceive field components in one or two dimensions. Here, we report an approach to fabricate high-density integrated active matrix magnetic sensor with three-dimensional (3D) magnetic vector field sensing capability. The 3D magnetic sensor is composed of an array of self-assembled micro-origami cubic architectures with biased anisotropic magnetoresistance (AMR) sensors manufactured in a wafer-scale process. Integrating the 3D magnetic sensors into an e-skin with embedded magnetic hairs enables real-time multidirectional tactile perception. We demonstrate a versatile approach for the fabrication of active matrix integrated 3D sensor arrays using micro-origami and pave the way for new electronic devices relying on the autonomous rearrangement of functional elements in space.
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    Dynamic Network Characteristics of Power-electronics-based Power Systems
    ([London] : Macmillan Publishers Limited, part of Springer Nature, 2020) Ji, Yuxi; He, Wei; Cheng, Shijie; Kurths, Jürgen; Zhan, Meng
    Power flow studies in traditional power systems aim to uncover the stationary relationship between voltage amplitude and phase and active and reactive powers; they are important for both stationary and dynamic power system analysis. With the increasing penetration of large-scale power electronics devices including renewable generations interfaced with converters, the power systems become gradually power-electronics-dominant and correspondingly their dynamical behavior changes substantially. Due to the fast dynamics of converters, such as AC current controller, the quasi-stationary state approximation, which has been widely used in power systems, is no longer appropriate and should be reexamined. In this paper, for a better description of network characteristics, we develop a novel concept of dynamic power flow and uncover an explicit dynamic relation between the instantaneous powers and the voltage vectors. This mathematical relation has been well verified by simulations on transient analysis of a small power-electronics-based power system, and a small-signal frequency-domain stability analysis of a voltage source converter connected to an infinitely strong bus. These results demonstrate the applicability of the proposed method and shed an improved light on our understanding of power-electronics-dominant power systems, whose dynamical nature remains obscure.