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Abstract This study extends an energy-balance-equation wave model (a phase-averaging wave model) for multidirectional random wave transformations to account for wave shoaling, refraction, diffraction, reflection and breaking. Quadratic upstream interpolation for convective kinematics is used in the discretization to reduce numerical diffusion. Predictions using the present wave model are compared with Sommerfeld's solutions for wave transformation through a gap between breakwaters, experimental observations for wave transformation due to a circular shoal, and field measurements for waves behind a breakwater. The results of these comparisons show fairly good agreement.

Photoelectronic responses of organic-inorganic hybrid perovskite CH 3 NH 3 PbI 3 on mesoporous TiO 2 electrodes are investigated. On the basis of near-band-edge optical absorption and photoluminescence spectra, the bandgap energy and exciton binding energy as a function of temperature are obtained. The exciton binding energy is much smaller than thermal energy at room temperature, which means that most excitons are thermally dissociated, and optical processes are determined by the photoexcited electrons and holes. We determined the temperature dependence of exciton binding energy, which changes from ~30 meV at 13 K to 6 meV at 300 K. In addition, the bandgap energy and the exciton binding energy show abrupt changes at 150 K due to structural phase transition. Our fundamental optical studies provide essential information for improving the device performance of solar cells based on halide perovskite semiconductors.

The concept of resilience is a crucial part in crafting visions of desirable futures designed to withstand the widest variety of external shocks to the system. Backcasting scenarios are widely used to envision desirable futures with a discontinuous change from the present in mind. However, less effort has been devoted to developing theoretical frameworks and methods for building backcasting scenarios with a particular focus on resilience, although resilience has been explored in related sustainability fields. This paper proposes a method that helps design backcasting scenarios for resilient futures. A characteristic of the method is to delineate “collapse” futures, based upon which resilient futures are described to avoid the various collapsed states. In the process of designing backcasting scenarios, fault tree analysis (FTA) is used to support the generation of various risk factors and countermeasures to improve resilience. In order to test the effectiveness of the proposed method, we provide a case study to describe resilient energy systems for a Japanese community to 2030. Four expert workshops involving researchers from different disciplines were organized to generate diversified ideas on resilient energy systems. The results show that three scenarios of collapsed energy systems were described, in which policy options to be taken toward achieving resilient energy systems were derived.

Abstract Cup-stacked carbon nanotubes (CSCNT) with different surface properties were used for the non-aqueous Li–O 2 battery cathodes, and then examined at high magnification to understand how the discharge products were deposited on the cathode. As-prepared CSCNT based cathode had many reactive edges consisting of truncated conical graphene layers. After discharge, discharge products with average particle size 50 nm covered a nanotube, resulting in a layer-like texture. On the other hand, a heat-treated CSCNT based cathode was composed of edges terminated by graphitization of several graphene layers. After discharge, the size of the products was almost the same but the products were agglomerated, forming a bulky morphology. It was, thus, found that the carbon surface structure was closely related with the morphology of the cathode deposits after discharge. First principles calculations also indicated that no terminated edges acted as preferential active sites in adsorbing and storing the reaction species. It was, therefore, concluded that the active edges of the carbon surface were indispensable for controlling the morphology of cathode deposits and improving the battery performance.

Abstract Unsteady aerodynamic lift force and pitching moment for a 2-D rectangular cross section are evaluated by the discrete vortex method. The section is in coupled oscillation for heaving/torsional 2 d.o.f. The results are discussed by comparison with the data from wind tunnel experiments and with the analytical values determined by the non-stationary thin airfoil theory (Theodorsen function).

AbstractW2N films with metallic luster are obtained by chemical vapor deposition at 450‐600 °C using a molar ratio of the WF6/NH3/H2 gas mixture of 1:4:(1‐2).

The impedance of polyacetylene has been measured in electrolyte solutions of LiClO4, LiPF6 or LiBF4 in propylene carbonate (PC). In the high frequency range, an impedance corresponding to a charge-transfer reaction has been observed in each electrolyte. The charge-transfer resistance has been estimated from the impedance measurement and has the lowest value in PC-LiClO4.

2,3-Butanediol (2,3-BDO) has gained much attention due to its bulk chemical uses in numerous applications such as the production of pharmaceuticals, cosmetics, synthetic rubber, inks, resins, perfumes, foodstuffs, fuel additives, and aviation fuel.