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The authors propose a phased patch-antenna array working in the X-band (i.e. 8-12 GHz), in which the beam-steering is obtained by means of two-terminal non-volatile resistive switches (or memristors). These novel components have a simple design and a tunable resistance (suitable for electromagnetic matching), and could replace other volatile switching-type devices (such as PIN diodes, MEMS, etc.), providing good radiofrequency (RF) performance and low-power consumption. They also offer the advantage of non-volatility state, i.e. the controlling signals do not need to be applied continuously, which entails a decrease of the power consumption and a reduction of antenna's sensitivity to power outages. The paper models a simple non- volatile resistive switch working in the microwave and millimetre frequency bands, then simulates, based on these switches, a frequency-tunable dipole antenna and a double patch-antenna array with beam steering capabilities. The authors obtained a multi-resonant array, which exhibits a maximum steering angle of ±28°. They also report the fabrication and characterisation of a resistive switch, based on TiO2-x that shows promising performance for high endurance and retention, with low insertion loss and high isolation. The results of this study represent the starting point for a new family of microwave tunable devices. [ABSTRACT FROM AUTHOR]

This paper presents an optimization analysis of an axial flux-switching hybrid excitation synchronous machine (AFHESM) to improve its no-load electromagnetic performances. The shapes of permanent magnet (PM), rotor-teeth and stator slot of AFHESM are investigated for a better design scheme by finite element analysis (FEA). Some optimal results under no-load are achieved, which mainly including the induced electromotive force (EMF), cogging torque and field control ability. Both FEA and experimental results show that the induced EMF can be improved when PM shape coefficient is 0.95 and the rotor-teeth bevel angle is 6°. [ABSTRACT FROM AUTHOR]

Dispersing inorganic colloidal nanoparticles within nematic liquid crystals provides a versatile platform both for forming new soft matter phases and for predefining physical behavior through mesoscale molecular‐colloidal self‐organization. However, owing to formation of particle‐induced singular defects and complex elasticity‐mediated interactions, this approach has been implemented mainly just for colloidal nanorods and nanoplatelets, limiting its potential technological utility. Here, orientationally ordered nematic colloidal dispersions are reported of pentagonal gold bipyramids that exhibit narrow but controlled polarization‐dependent surface plasmon resonance spectra and facile electric switching. Bipyramids tend to orient with their C5 rotation symmetry axes along the nematic director, exhibiting spatially homogeneous density within aligned samples. Topological solitons, like heliknotons, allow for spatial reorganization of these nanoparticles according to elastic free energy density within their micrometer‐scale structures. With the nanoparticle orientations slaved to the nematic director and being switched by low voltages ≈1 V within a fraction of a second, these plasmonic composite materials are of interest for technological uses like color filters and plasmonic polarizers, as well as may lead to the development of unusual nematic phases, like pentatic liquid crystals. [ABSTRACT FROM AUTHOR]

Morphological properties of surfaces play a key role in natural and man‐made objects. The development of robust methods to fabricate micro/nano surface structures has been a long pursuit. Herein, an approach based on molecular self‐assembling of liquid crystal polymers (LCPs) is presented to directly translate 2D molecular director profiles obtained by a photoalignment procedure into 3D topographies, without involving further multi‐step lithographic processes. The principle of surface deformation from a flat morphology into complex topographies is based on the coupling between electrostatic interactions and the anisotropic flow in LCPs. When activated by an electric field, the LCP melts and is driven by electrohydrodynamic instabilities to connect the electrode plates of a capacitor, inducing topographies governed by the director profile of the LCP. Upon switching off the electric field, the formed structures vitrify as the temperature decreases below the glass transition. When heated, the process is reversible as the formed topographies disappear. By pre‐programming the molecular director a variety of structures could be made with increasing complexity. The height, pitch, and the aspect ratio of the textures are further regulated by the conditions of the applied electric field. The proposed approach will open new opportunities for optical and electrical applications. [ABSTRACT FROM AUTHOR]