Hydroelastic vibration of the bottom plate of the cylindrical tank coupled with sloshing

Journal of Mechanical Science and Technology - This study is concerned with the hydroelastic vibration of the flexible bottom plate of a cylindrical tank coupled with sloshing. The cylindrical tank...     

Stability boundary analysis of magnetohydrodynamic circulator for the intermediate heat transfer system of prototype gen IV sodium fast reactor

One of the most important parts in the development of generation IV nuclear reactors is safety. In the research on generation IV sodium‐cooled fast reactors, magnetohydrodynamic (MHD) circulators have received attention for the stable transport of coolants. In this study, the stability of an MHD circulator was evaluated using a mathematical approach to obtain the critical value of the developed pressure. The critical developed pressure equation is a function of the flow rate and dimensionless parameters, which were derived from the theoretical model of the MHD circulator with a dimensionless scaled velocity, flow rate, and pressure. The stability conditions expressed using the critical value of the developed pressure and dimensionless parameters were investigated according to the changes in the main design variables of the MHD circulator. The relationships between the dimensionless parameters, stability, and main design variables constituting the stability boundary of the MHD circulator were analysed. The stability of the MHD circulator is considered safe when the stability criterion ε is lower than 1. The geometrical variables such as the duct thickness or width of the flow gap and electrical variables such as the frequency were the main parameters affecting the flow stability in the MHD circulator.     

Electrohydrodynamic (EHD) enhancement of boiling heat transfer of R 113+WT4% ethanol

Nucleate boiling heat transfer for refrigerants, R113, and R113+ wt4% ethanol mixture, an azeotropic mixture under electric field was investigated experimentally in a single-tube shell/ tube heat exchanger. A special electrode configuration which provides a more uniform electric field that produces more higher voltage limit against the dielectric breakdown was used in this study. Experimental study has revealed that the electrical charge relaxation time is an important parameter for the boiling heat transfer enhancement under electric field. Up to 1210% enhancement of boiling heat transfer was obtained for R113+wt4% ethanol mixture which has the electrical charge relaxation time of 0.0053 sec whereas only 280% enhancement obtained for R113 which has relaxation time of 0.97 sec. With artificially machined boiling surface, more enhancement in the heat transfer coefficient in the azeotropic mixture was obtained.     

Experimental study of acoustic characteristics of expansion chamber with mean flows

For the measurement of transmission loss of the silencers which have mean flow, the noise levels of signals depicted by microphone usually prohibit accurate measurements of the transmission loss. To overcome this difficulty, static pressure compensation technique has been developed to increase the dynamic range of the microphones, resulting accurate measurement of transmission loss in the presence of high noise level. Series of experiments to investigate the acoustic characteristics of expansion chamber with mean flow has been performed using the pressure compensated microphones. Results demonstrate: (1) frequency shift due to the presence of mean flow, (2) effect of length, diameter, offset length and twisting angles to the transmission loss of expansion chamber with and without mean flow (up to 50m/sec), (3) relation between the proposed parameter ‘aspect ratio’ and number of peaks of transmission loss in low frequency region.     

Organic Semiconductor Cocrystal for Highly Conductive Lithium Host Electrode

In this work, a highly conductive organic cocrystal is investigated as an anode material for conducting agent‐free lithium‐ion battery (LIB) electrodes. A unique morphology of semiconducting fullerene (C₆₀) and contorted hexabenzocoronene (cHBC) is developed as a cocrystal that efficiently enhances the electron transfer during discharge and charge processes due to the formation of a well‐defined junction between C₆₀ and cHBC. In particular, the present study reveals the exact cocrystal phase of orthorhombic Pnnm using grazing incidence X‐ray diffraction characterization and computational methods. The detailed cocrystal structure analysis indicates that the columnar structure of C₆₀/cHBC cocrystal facilitates the reliable vacant sites for Li⁺ storage, which ultimately enhances the reversible capacity to 330 mAh g^–1 at 0.1 A g^–1 with long cyclability of 600 cycles in the absence of a conducting agent. Furthermore, the rate performance of the C₆₀/cHBC cocrystal anode is improved compared to that of the graphite anode, indicating that the cocrystal formation between C₆₀ and cHBC enhances the charge transport at a high current density. It demonstrates that the approach of this study can be a promising strategy for preparing conducting agent‐free organic cocrystal anodes, which also provides a viable design rule for high‐performance LIBs electrodes.     

Affective social big data generation algorithm for autonomous controls by CRNN-based end-to-end controls

Multimedia Tools and Applications - Affective social multimedia computing provides us the opportunity to improve our daily lives. Various things, such as devices in ubiquitous computing...     

Ruthenium Nanoparticles on Cobalt‐Doped 1T′ Phase MoS2 Nanosheets for Overall Water Splitting

2D MoS₂ nanostructures have recently attracted considerable attention because of their outstanding electrocatalytic properties. The synthesis of unique Co–Ru–MoS₂ hybrid nanosheets with excellent catalytic activity toward overall water splitting in alkaline solution is reported. 1T′ phase MoS₂ nanosheets are doped homogeneously with Co atoms and decorated with Ru nanoparticles. The catalytic performance of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is characterized by low overpotentials of 52 and 308 mV at 10 mA cm^?2 and Tafel slopes of 55 and 50 mV decade^?1 in 1.0 m KOH, respectively. Analysis of X‐ray photoelectron and absorption spectra of the catalysts show that the MoS₂ well retained its metallic 1T′ phase, which guarantees good electrical conductivity during the reaction. The Gibbs free energy calculation for the reaction pathway in alkaline electrolyte confirms that the Ru nanoparticles on the Co‐doped MoS₂ greatly enhance the HER activity. Water adsorption and dissociation take place favorably on the Ru, and the doped Co further catalyzes HER by making the reaction intermediates more favorable. The high OER performance is attributed to the catalytically active RuO₂ nanoparticles that are produced via oxidation of Ru nanoparticles.     

Unraveling the Water Impermeability Discrepancy in CVD‐Grown Graphene

Graphene has recently attracted particular interest as a flexible barrier film preventing permeation of gases and moistures. However, it has been proved to be exceptionally challenging to develop large‐scale graphene films with little oxygen and moisture permeation suitable for industrial uses, mainly due to the presence of nanometer‐sized defects of obscure origins. Here, the origins of water permeable routes on graphene‐coated Cu foils are investigated by observing the micrometer‐sized rusts in the underlying Cu substrates, and a site‐selective passivation method of the nanometer‐sized routes is devised. It is revealed that nanometer‐sized holes or cracks are primarily concentrated on graphene wrinkles rather than on other structural imperfections, resulting in severe degradation of its water impermeability. They are found to be predominantly induced by the delamination of graphene bound to Cu as a release of thermal stress during the cooling stage after graphene growth, especially at the intersection of the Cu step edges and wrinkles owing to their higher adhesion energy. Furthermore, the investigated routes are site‐selectively passivated by an electron‐beam‐induced amorphous carbon layer, thus a substantial improvement in water impermeability is achieved. This approach is likely to be extended for offering novel barrier properties in flexible films based on graphene and on other atomic crystals.