An Air Velocity Monitor for Coal Mine Ventilation Based on Vortex-Induced Triboelectric Nanogenerator.

Air velocity of coal mine ventilation is an important consideration that may cause serious damage. This paper proposes a simple, low cost and effective air velocity monitor (AVM) for coal mine ventilation. The AVM uses the lock-in characteristic of vortex-induced vibration (VIV) to sense the air velocity. Amplitude of the VIV is converted into frequency signal of a vortex-induced triboelectric nanogenerator (VI-TENG) to improve the durability. Structure of the AVM are designed, and parameters of the AVM are optimized with experiments. For the upper and lower air velocity thresholds of 3.1 and 3.6 m/s, the optimized flexible beam length, slider weight, electrode space and electrode width are 42.5 mm, 0.4 g, 0.2 mm and 0.5 mm, respectively. Experiments also show that the output frequency of the VI-TENG could represent the amplitude of VIV well with the correlation coefficient of 0.93. Durability test demonstrates that the AVM generates stable output frequency in 120,000 cycles. A prototype and its controller are fabricated. Wind tunnel tests of this prototype show that it can give alarm when the gas velocity goes above the upper threshold or below the lower threshold. The proposed AVM could be a good solution for simple and effective coal mine ventilation alarm.

Ruthenium Carbonyl Clusters in Faujasite Cages: Synthesis and Characterization.

The synthesis of the intrafaujasite anchoring of ruthenium carbonyl clusters involves the adsorption of metal carbonyl species or metal ion exchange into faujasite cages followed by reductive carbonylation under an atmosphere of CO and H(2). The characterization of the structure and properties of these samples was based on a multianalytical approach, including FT-IR, UV-vis, PXRD, and EXAFS spectroscopies, CO/H(2) gas chemisorption, and (13)CO isotopic exchange. From this study, several key points emerge. (a) [Ru(3)(CO)(12)] clusters thermally diffused into dehydrated faujasite cages. (b) [Ru(3)(CO)(12)] guests in Na(56)Y were thermally activated, in a hydrogen atmosphere, generating intrafaujasite [H(4)Ru(4)(CO)(12)]. (c) Hexammineruthenium(III) complexes in Na(56)X and Na(56)Y underwent progressive thermal activation, in a CO and H(2) atmosphere. The generation process was considered to occur through conversion of the intermediates [Ru(NH(3))(5)(CO)](2+) and Ru(I)(CO)(3) to [Ru(6)(CO)(18)](2)(-). (d) A rapid (13)CO/(12)CO isotopic exchange was found to reversibly occur for [Ru(6)(CO)(18)](2)(-)/Na(56)X under H(2) coexistence. (e) Internal and external confinement of ruthenium carbonyl clusters were compared. (f) Oxidation fragmentation under an O(2) atmosphere and reductive regeneration under a CO and H(2) atmosphere were found to reversibly occur for [Ru(6)(CO)(18)](2)(-) guests. (g) Intrafaujasite anchoring of ruthenium carbonyl clusters showed a strong interaction with the extraframework Na(+) alpha-cage cations, through involvement of the oxygen end of the bridging or equatorial terminal carbonyl ligands.