An experimental investigation of the breakup characteristics of secondary atomization of emulsified fuel droplet

In this study, the breakup characteristics of secondary atomization of an emulsified fuel droplet were investigated with a single droplet experiment. In the single droplet experiment, the emulsified fuel droplet suspended from a fine wire was inserted into an electric furnace, and then secondary atomization behavior was observed using a high-speed video camera. Moreover, a mathematical model to calculate the generated water vapor at micro-explosion was proposed by using the mass and energy conservation equations under some assumptions. In the proposed model, that can be calculated by using the inner droplet temperature history at micro-explosion. As a result, puffing and micro-explosion occurred even when the fine ceramics fiber was used. The proposed model showed that about 50–70 wt% of water in the emulsified fuel changed to water vapor instantaneously at the occurrence of micro-explosion. The mass of water necessary for micro-explosion was shown. The breakup time was closely related to the superheat temperature just before the occurrence of micro-explosion.     

Collision Drag Effect on Two-Fluid Hydrodynamics of Superfluid 3He in Aerogel

Sound propagation in superfluid ³He in aerogel is studied on the basis of a two-fluid model taking into account the effect by the drag force due to collisions between ³He-quasiparticles and aerogel molecules. The drag force plays a role of frictional force between the aerogel and the normal-fluid component. In local equilibrium, they move together in accordance with McKenna et al.'s model. The deviation from the local equilibrium leads to the damping of sound. We give explicit expressions for the attenuation of longitudinal sounds in this system. We also discuss the sound propagation in a superfluid ³He-aerogel system embedded in a narrow pore. It is shown that the fourth sound propagates in such a system because of the clamping of the normal fluid by the aerogel.     

An improved fully stressed design algorithm for plate/shell structures

The stress-ratio algorithm associated with fully stressed design philosophy has been used as a convenient tool to achieve minimum weight design of strength-limited structures. The algorithm is effective and converges quickly for many cases. However, it presents extremely slow oscillatory iteration histories for plate-thickness design problems that involve transverse bending loads. Modification of the basic algorithm presented in this paper provides an effective remedy to this problem when both membrane and bending loads are present. The modified resizing algorithm requires numerical solutions of a fourth-order algebraic equation. No additional data, beyond the ordinary static analysis results, are required.     

Spatial distribution of minority-carrier lifetime and local concentration of impurities in multicrystalline silicon solar cells

Spatial distribution of minority-carrier lifetime (τ) in multicrystalline silicon solar cells was investigated. By mapping of τ, a wide distribution in a higher-efficiency cell and a narrow distribution in a lower-efficiency cell was found, respectively. Based on the relation between τ and the density of grain boundaries, spatial distribution of impurities was characterized by secondary ion mass spectrometry. To clarify the spatial profile near grain boundaries, a method of changing detection area was carried out. Iron (Fe) segregation within 100 μm around a grain boundary was observed. In the lower-efficiency cell, a measurable amount of Fe was contained in a crystalline area as well.     

Compact ARROW-type vertical coupler filter

Compact wavelength filter utilizing the vertical coupling between a conventional ridge waveguide and a 3-D ARROW is proposed and demonstrated. Compact size and narrowband performance are achieved utilizing the large difference of waveguide dispersion between the 3-D ARROW and the ridge waveguide at single mode. A polyimide ridge waveguide was stacked on a stripe lateral confinement ARROW in an intersecting configuration with the interaction length of about 1 mm, and -3-dB linewidth of 5.5 nm was experimentally achieved.     

A fading reduction method for maritime satellite communications

A maritime satellite communication system has been established mainly for large vessels. In the near future it will be expected to service not only large vessels but also small ones. Studies on reducing the fading of the received signals have become very important because a compact antenna designed to be mounted on small vessels has a broad beamwidth which can be greatly influenced by reflected waves from the sea surface. A simple method and antenna equipment which can reduce the fading are proposed and, further, the effects by experiments are confirmed.     

Varying mode of disorder of the MnAl6 alloy phase in the recovery process of vacuum codeposited films

Mn-Al films with different compositions ranging from 8 to 21 at.% Mn were prepared by simultaneous vacuum codeposition and their crystallization during a temperature rise was investigated by transmission electron microscopy. The film whose composition is exactly that of the MnAl₆ phase shows discrete nucleation of MnAl₆ crystals and they grow in a beautiful circular form. As the manganese content of the film increases from that of MnAl₆, the crystals grow in circular, in blade-like and in avalanche-like form, respectively. Diffraction patterns of these crystals show that they have a differently disordered MnAl₆ lattice and that the modes of disorder depend on the film composition. Extra spots, diffuse streaks and a deficiency of spots were observed in the respective crystals and almost all of them can be interpreted as being due to disorder in the stacking of atomic planes parallel to the (001) plane of the MnAl₆ lattice. A model of the atomic arrangement is proposed to account for the deficiency of spots.