ABSTRACT:The effects of spin-friction pressure and timing on the friction welding between parts of the same materials, PP, HDPE, and nylon-6, are discussed. The heataffected zone is divided into three regions: the plasticized region (Zpl), the partly plasticized region (Zpd), and the undeformed region (Zud). The tensile fracture morphology has three main sections: the nonplasticized central section (Fud), the plasticized peripheral section (Fpl), and the partly plasticized section between Fud and Fpl (Fpd). Friction pressures (spinning timing) of 1.17 MPa (16 s) in PP-PP welding, 1.77 MPa (8 s) in HDPE-HDPE welding, and 0.98 MPa (8, 10, and 12 s) in nylon-6 -nylon-6 welding attains better bonding strength because their components have larger Fpd and Fpl regions, which have no Fud in the central part.
Due to the COVID-19 virus being highly transmittable, frequently cleaning and disinfecting facilities is common guidance in public places. However, the more often the environment is cleaned, the higher the risk of cleaning staff getting infected. Therefore, strong demand for sanitizing areas in automatic modes is undoubtedly expected. In this paper, an autonomous disinfection vehicle with an Ultraviolet-C (UVC) lamp is designed and implemented using an ultra-wideband (UWB) positioning sensor. The UVC dose for 90% inactivation of the reproductive ability of COVID-19 is 41.7 J/m2, which a 40 W UVC lamp can achieve within a 1.6 m distance for an exposure time of 30 s. With this UVC lamp, the disinfection vehicle can effectively sterilize in various scenarios. In addition, the high-accuracy UWB positioning system, with the time difference of arrival (TDOA) algorithm, is also studied for autonomous vehicle navigation in indoor environments. The number of UWB tags that use a synchronization protocol between UWB anchors can be unlimited. Moreover, this proposed Gradient Descent (GD), which uses Taylor method, is a high-efficient algorithm for finding the optimal position for real-time computation due to its low error and short calculating time. The generalized traversal path planning procedure, with the edge searching method, is presented to improve the efficiency of autonomous navigation. The average error of the practical navigation demonstrated in the meeting room is 0.10 m. The scalability of the designed system to different application scenarios is also discussed and experimentally demonstrated. Hence, the usefulness of the proposed UWB sensor applied to UVC disinfection vehicles to prevent COVID-19 infection is verified by employing it to sterilize indoor environments without human operation.
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