An approach to higher damping capacity based on a control theory strategy

In order to compare the active damping (computer-controlled damping) via a control theory with the passive (material) damping, the vibration suppressing effect has been investigated by constructing a feedback control system. It consists of a cantilever beam (3×35×300 mm³), a sensor, an actuator and a feedback controller, which has been designed on the basis of the optimal regulator control theory. In a freely decaying vibration state, the active damping effect increases the vibration damping capacity (Q⁻¹) from 0.011 to 0.157 (almost 14.3 times). On the other hand, in a resonant state, the active damping reduces the resonant amplitude to about 1/12. The active damping corresponds to about 6.8 times the maximum damping observed in the ferromagnetic metal SIA.     

Study on the generation process of the discharge for color plasmadisplays based on observation by using an ultra-high-speed electroniccamera

Instead of the direct observation of ultraviolet rays of 147 nm emitted from Xe, light emission of 828 nm was observed first by using ultra-high-speed electronic camera system. The experimental results show that the ultraviolet rays of 147 nm emit above both cathodes and anodes simultaneously. The striation phenomena observed on anodes were analyzed     

Experimental study on porous current collectors of PEM electrolyzers

Experimental study on proton exchange membrane (PEM) electrolyzer was carried out focusing on the effect of pore structural properties of current collectors, such as porosity and pore diameter. Various titanium (Ti)-felt substrates with different porosities and pore diameters (measured by capillary flow porometry) were used as the anode current collector. Results show that when the mean pore diameter of the current collector was larger than 10 μm, the electrolysis performance improved with decreasing pore diameter. In contrast, changes in porosity had no significant effect on the cell performance when the porosity exceeded 0.50. The flow pattern of two-phase flow in the flow channel was discussed in terms of its relationship to bubble size and to pore diameter of the current collector. Finally, correlation between the calculated membrane resistance and the measured pore diameter of the current collectors suggest that larger bubbles generated from larger pores tend to become long bubbles in the channel, thus hindering the water supply to the membrane.     

Interfacial modification and impact properties of Nb/MoSi2 laminate composites by the addition of ZrO2, NbSi2, and SiC particles

In this study, the results of a thermodynamical estimation indicate that the impact properties of Nb/MoSi₂ laminate composites can be improved by suppressing the interfacial reaction. The effects of addition of SiC, NbSi₂, and ZrO₂ on the impact properties and interfacial reaction of Nb/MoSi₂ laminate composites are also examined. Laminate composites, which comprise alternate layers of matrix mixture and Nb foil, were fabricated by the hot press process. Addition of ZrO₂ particle is clearly demonstrated to increase both the impact value and the sintered density of Nb/MoSi₂ laminate composites. The thickness of the interfacial reaction layer in Nb/MoSi₂ laminate composites dramatically decreases with increasing volume fraction of ZrO₂ particle. The suppression of the interfacial reaction is caused by the formation of ZrSiO₄ in the MoSi₂-ZrO₂ matrix mixture. In addition, it appears that the reduction of the reaction layer promotes the plastic deformation of Nb foil and the interfacial delamination in laminate composites.     

Time-resolved electrochemical measurement device for microscopic liquid interfaces during droplet formation

An electrochemical measurement system with a high-speed camera for observation of dynamic behavior of ionic molecules at a water-in-oil interface during microfluidic droplet formation is described. In order to demonstrate the usefulness of the system, a liquid interface between 1 M sodium chloride aqueous solution and 0.02 M tetrabutylammonium tetraphenylborate 1,2-dichloroethane solution was investigated. During aqueous droplet formation in a microfluidic device, averaged and dynamic currents between the two phases were measured under potential control. The measured current corresponded to the transport of electrolyte ions to form the electrical double layer at the liquid interface. When an 18-μm-sized droplet was formed in each 1.2 ms, the amount of charge on each droplet was measured to be 20 pC at 0.4 V and negligible at the potential of zero charge (0.19 V). In addition, the high-speed camera observations revealed that the charge affects the stability of the droplet during and/or just after the generation process. This measurement system is expected to facilitate a fuller understanding of the droplet formation process.     

Thermal Behavior of Potato Starch and Water-Vaporization Behavior of Its Paste Controlled with Amino Acid and Peptide-Rich Food Materials

ABSTRACT: The particular effect of 4 kinds of amino acid and peptide-rich food material (APRM) containing different charged amino acid contents on the gelatinization and retrogradation behavior of potato starch granules and on the water-vaporization behavior was analyzed by differential scanning calorimetry, rapid viscoanalysis, x-ray diffractometry, thermal gravimetry-differential thermal analysis, and pulsed NMR. APRM with a high-charged amino acid content produced unique gelatinization and retrogradation behavior in terms of an elevated gelatinization temperature, reduced viscosity, higher setback, and lower retrograded starch melting enthalpy. The recovered x-ray diffraction intensity decreased with increasing charged amino acid content. APRM with high-charged amino acid content could provide an improved paste having easy vaporization of external water in the swollen starch granules due to the reduced swelling.     

Polymorphism of Extended Fullerene Networks: Geometrical Parameters and Electronic Structures

Abstract

The morphology of fullerene networks can be widely extended by introducing heptagonal or octagonal rings, which produce a Gaussian negative curvature. Their presence makes it possible to form donut-, coil- and sponge-shaped networks of carbon atoms. We discuss the geometry of the polymorphous forms based on the net diagram method relative to a honeycomb lattice, and further study the electronic structures constructed by the network of electrons system. Special emphasis is put on how the geometrical paramateres, which specify the relative arrangement of polygonal ring, control the electronic structures in the various extended-fullerene networks. In addition, we mention that the presence of a certain type of edge in fullerene network derives critical localized edge stages at the Fermi level.     

Photophysical properties and photostability of novel symmetric polycyclicphenazine-type fluorescent dyes and the dye-doped films

Novel symmetric polycyclicphenazine-type fluorescent dyes have been synthesized and characterized in solution and in polymer films. The dyes exhibited two strong absorption bands at around 365-428 nm and 519-567 nm and an intense fluorescence band at around 560-600 nm (Ф = 0.70-0.87) in 1,4-dioxane. The dye-doped polymer films showed excellent wavelength conversion function that efficiently convert ultraviolet and yellow lights into red light (Ф = 0.61-0.92). Moreover, the photostability of the dye-doped PS, PMMA, and PLA films has been investigated.     

Effect of loading schedule on densification of MgAl2O4 spinel during spark plasma sintering (SPS) processing

An increase in the loading temperature during SPS processing can reduce the residual porosity in a spinel and thus attain a high transmission even at the high heating rate of 100 °C/min. This suggests that load controlling is an important factor as well as the heating rate and sintering temperature. Although the transmission is lower than the maximum value attained at the low heating rates of <10 °C/min, the loading schedule optimization enables utilization of the high heating rate processing that is a primary advantage of the SPS technique.