Search

In order to develop a vaccination system that have no contact with healthcare workers during highly transmissible epidemics, a portable modular vaccine injection system (PMVIS) composed of YT-type modules (YTM), winding modules (WM) and an active injector (AI) actuated by shape memory alloy (SMA) wires are proposed in this article. By series layout of WMs, YTMs and AI, the multi-posture requirements of PMVIS can be realized. Then, the thermodynamic model of SMA together with kinematic and dynamic models of structure for each module are established, and studied the output stroke of each module through numerical analysis and experiments. The results show that the designed YTM achieves a maximum output of 1.84 mm displacement or 1.9° angle under the given size parameters. After connecting 1-WM in series, the output displacement and rotation angle are enlarged to 12.12 mm and 10.8°, which are increased by 558.7% and 468.4%, respectively. PMVIS can realize multi-postures through different functional modules to play the role of position adjustment. It provides theoretical and technical support for future contactless injection systems. [ABSTRACT FROM AUTHOR]

In this work, a polarization conversion metasurface is proposed, which can convert linearly polarized electromagnetic (EM) waves into cross-polarized waves in ultra-wideband at high polarization conversion efficiency. The proposed sandwiched metasurface, composed of a top anisotropic resonator structure, an intermediate dielectric substrate, and a bottom metallic ground, has an extremely thin thickness (only 6.6% of the longest wavelength of the working frequency range). Both numerical simulation and experimental results illustrate that the metasurface can work in the ultra-wideband (ranging from 9.04 to 20.83 GHz) with a high polarization conversion ratio (>0.9). Polarization conversion in a wide bandwidth is attributed to multiple resonances in the operating frequency range. Additionally, the proposed metasurface also shows good performance for oblique incidence. It is expected that the designed metasurface will be more convenient for integration within ultra-thin EM devices. [ABSTRACT FROM AUTHOR]

In this paper, a non-uniform strip-array decoupling structure (SADS) of the MIMO antenna-arrays for the dedicated short-range communication (DSRC) applications in intelligent transportation systems (ITS) is presented. The SADS is composed of metal strips with non-uniform longitudinal layout, which has a simple strip-array geometry, low design and fabrication complexity, and easy to be applied to the design domain without destroying the original antenna-array. The design of the strip thickness, strip-array layout and number of strips is realised by the proposed simple and effective optimisation method. The mutual coupling between the elements can be effectively suppressed to less than −32 dB by the proposed structure in the required bandwidth (5.795 GHz~5.815 GHz). The results show that, compared with the no-strip and uniform SADS, the non-uniform SADS can improve the maximum mutual coupling reduction by 23 dB and 13 dB, respectively. Both the simulated and measured results verify the effectiveness of the proposed SADS, which makes it very suitable for the large-scale MIMO antenna-arrays. [ABSTRACT FROM AUTHOR]