In
this work, g-C3N4@TiO2 nanostructures
with hollow sphere morphology, small grain size, high crystalline quality, and high surface area
are successfully synthesized by the annealing method using melamine
and hollowsphere precursor, which could be a universal method to synthesis
hollow sphere nanoheterojunction. Excellent photocatalytic property
was observed from the as-prepared g-C3N4@TiO2 nanostructure with 466.43 μmol·g–1·h–1 hydrogen generation rate under visible
light irradiation (>420 nm), which was 5.5 times as much as the
control
couple, nanoparticle nanoheterojunction g-C3N4@TiO2. No apparent deactivation was found during the follow-up
cycle performance test. The special morphology and the heterojunction
construction contribute to both visible light absorption and photogenerated
electron–hole pair separation efficiency and finally to the
photocatalytic property. The content of g-C3N4 was proved to be an important parameter for the promotion of the
photocatalytic property. Overlarge content may lead to lower photogenerated
electron–hole pair separation efficiency.
Biologists have reported that fish form sensory maps to assist in the imaging of flow disturbances underwater, including those created by predator or prey, using the lateral-line flow-sensing system. Our group has invented artificial lateral-line systems based on both micromachined and commercial hot-wire anemometer sensors. In this paper, we report on the successful application of adaptive beamforming (Capon's method), in conjunction with an artificial lateral line, to visualize flow disturbances, including acoustic dipoles, underwater. Our preliminary results showcase, for the first time, an ability to image an entire region underwater using micro and millimeter scale arrays, thereby mimicking the flow-imaging abilities of fish.Index Terms-Fluid flow measurement, underwater acoustic transducers, fluids, array signal processing, dipole arrays, anemometers, adaptive beamforming.
For large space buildings like industrial plants with huge heat generation, the role that surface-source plumes play becomes more crucial. To study the air distribution and movement of plumes, the first step is to quantify how the airflow gets distributed in chambers. The experiment was carried out in a thermostatic chamber where there was no ventilation. Four hundred flow field snapshots (in each region) were measured by a two-dimensional particle image velocimetry system at a sampling frequency of 3 Hz, and the time-average flow field was processed by the adaptive correlation algorithm to quantify the air distribution of the plume. According to the measured data, the variation law of the axial velocity of the surface-source plume under different heat source parameters was analysed. The formula coefficients of the axial velocity, the extended radius and the mass flow of the plume were discussed, and the coefficients from current two mainstream methods and those obtained in this paper were compared. The results of this study will be useful to predict motion of surface-plumes and optimize airflow patterns in large spaces.
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