Discharge characteristics of latent heat storage columns packed with cross-linked plastic particles

This investigation deals with experimental and numerical analyses carried out to investigate the discharge characteristics of latent heat storage columns, using cross-linked cylindrical plastic particles as a phase-change type of heat storage material and ethylene glycol as a heat transfer medium. In the experiment, the transient response of the outlet temperature of the heat transfer medium was measured under conditions of varying the initial temperature in the column, the inlet temperature of the heat transfer medium, the mass flow rate of the heat transfer medium, and the mass of the heat storage material packed in the column. In the numerical analysis, the transient temperature distributions in the column was calculated by using an empirical formula for estimating the heat transfer coefficient for a fixed bed, which was recommended in the authors' previous paper. The experimental results were found to be in fair agreement with the numerical results. © 1998 Scripta Technica. Heat Trans Jpn Res, 26(3): 193–206, 1997     

Comparative study of switching methods for the on-board processor in a mobile satellite communications system

An on-board processor makes efficient use of the channel capacities in a satellite communications system employing multibeam technology, and an on-board processor has been developed for the Engineering Test Satellite VIII (ETS-VIII), which is the experimental satellite for a multibeam mobile satellite communications system. The multicarrier time division multiple access (MC-TDMA) system used in this communications system, however, sometimes causes internal congestion in the on-board processor. This paper describes the results of computer simulation studies of the traffic capacity obtained using three baseband switching methods and also describes the results of studies of the on-board processor design for each of the methods. The computer simulation results indicate that the probability of internal congestion due to the TDMA system is very small when the simultaneous-slot switching method is used, and the design study results reveal that an on-board processor using the simultaneous-slot switching method will be compact and lightweight and will consume little power. © 1998 John Wiley & Sons, Ltd.     

Spectral model and statistical parameters of biostimulation with 1/f fluctuation power

It has been widely accepted that physical stimulation—such as illumination, music, and environmental variables—that has a 1/f fluctuation power spectrum produces relaxation. There should, however, exist a number of stimulation waveforms that have 1/f power spectral characteristics, and thus the parameters of the waveform in the time domain that cause comfortable biostimulation remain unknown. As a first step in elucidating what kinds of biostimulation waveforms produce relaxation, this paper theoretically derives the CRD (crossing rate distribution: the number of times per second that the amplitude crosses various levels in the positive direction) and APD (amplitude probability distribution) for a Gaussian fluctuation waveform with a 1/f-like power spectrum. Flame fluctuation of candles, which is said to produce a sedative effect, is statistically measured. The findings obtained here show that the flame has a peak crossing rate between 0.08 and 0.4 Hz, fluctuating with a rhythm close to that of blood pressure (0.1 Hz) or breathing (0.25 to 0.33 Hz). © 1998 Scripta Technica. Electr Eng Jpn, 121(4): 48–55, 1997     

Progress of enantio-differentiating hydrogenation of prochiral ketones over asymmetrically modified nickel catalysts and a newly proposed enantio-differentiation model

This article reviews the enantio-differentiating hydrogenation of various prochiral ketones over asymmetrically modified Ni catalysts. Development from the discovery to the state of the art of the modified Ni catalyst is surveyed. Understanding and interpretation of this catalyst is discussed and new enantio-differentiation models are proposed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Light-emitting boron nitride nanoparticles encapsulated in zeolite ZSM-5

We report strong visible photoluminescence (PL) at room temperature from BN nanoparticles encapsulated in ZSM-5. The investigation of powder X-ray diffraction, X-ray photoelectron spectroscopy, adsorption of N₂, UV–Vis absorption, and PL spectra shows that BN nanoparticles have been successfully encapsulated in ZSM-5. Intense blue PL can be obtained from the BN/ZSM-5 sample. Analysis of PL spectra leads us to propose that the luminescence may originate from the bound excitons at the defects or impurities in the BN nanoparticles, a quasi-direct-gap semiconductor material transferred from indirect-gap BN by encapsulation in ZSM-5.     

Application of crystal plasticity to plastic behavior at notched plate and crack propagation

Strain concentration characteristics of ductile polycrystalline materials are studied experimentally and numerically by considering a notched square segment of material. The micromechanical modeling is performed using the finite element method based on crystal plasticity, while the material sample is taken to be FCC polycrystallline copper segment. The constitutive behavior is taken to be large-strain strain-rate-dependent elastic–plastic material. To effectively simulate polycrystalline behavior, the grain shape is generated from Voronoi tessellation, bearing a different lattice orientation in each grain. Strain concentration patterns around the notched bottom are observed experimentally and numerically, which are enlarged near the notch by accompanying a formation of localized strain accumulation toward an oblique direction. For the sample analyzed, with a relatively small macroscopic strain of 0.10, the notched bottom region experiences plastic strains as large as 1.00, and provides a strong indication that failure will initiate from the corner. Implications of this modeling study to microcracking failure are discussed by considering two fundamental modes of shear and cleavage to provide plausible microcracking examples.