Graphitic carbon nitride (g-C3N4) used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB) under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500) had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500), which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO) was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed.
To tackle the water surface pollution problem, a vision-based water surface garbage capture robot has been developed in our lab. In this article, we present a modified you only look once v3-based garbage detection method, allowing real-time and high-precision object detection in dynamic aquatic environments. More specifically, to improve the real-time detection performance, the detection scales of you only look once v3 are simplified from 3 to 2. Besides, to guarantee the accuracy of detection, the anchor boxes of our training data set are reclustered for replacing some of the original you only look once v3 prior anchor boxes that are not appropriate to our data set. By virtue of the proposed detection method, the capture robot has the capability of cleaning floating garbage in the field. Experimental results demonstrate that both detection speed and accuracy of the modified you only look once v3 are better than those of other object detection algorithms. The obtained results provide valuable insight into the high-speed detection and grasping of dynamic objects in complex aquatic environments autonomously and intelligently.
Water Strider Robot (WSR) is a kind of bio-inspired micro robot that can stand and move on water surface via surface tension. In this paper, a design method is presented with algorithms for designing driving leg. Structure, control system and software of the robot are also discussed in details. A prototype Water Dancer II-a that is driven with two electric motors is presented as successfully tested in lab. The proposed WSR is tele-controlled with infrared signals and has the capability of turning and speed regulation with features of light tiny volume and low power consumption. Experimental results are reported and discussed to show practical feasibility of the presented WSR prototype. The new results in the paper are related also to the WSR prototype design with a robot body of less than 30 × 30 mm size and with ten leg rods of 90 mm length and 0.2 diameter that are able to provide lifting force for a water walk of the 6.0 grams robot at a forward speed of 20 cm/s or angular velocity of 9 degree/s with two micro DC motors(RoomFlight 4 × 8 mm, 28 Ohm).
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