Reliability of prototype microcapsule diffuser for speckle noise reduction in laser displays

A microcapsule diffuser of the transparent type is proposed to reduce the speckle noise generated on a laser display. This diffuser has a microcapsule that is secured between two transparent electrodes. The microcapsule contains light diffusion particles that are electrically charged. Because the particles in the microcapsules are moved by the electric field, the proposed device reduces speckle noise. This paper reports the results of one study of the device reliability.     

Carbon nanowire formation in electron-energy controlled plasma produced by CH4/Ar rf discharges with small coaxial electrodes

Carbon nanowires are formed on a surface of nanoparticles made of diamond-like carbon produced on a nickel plate placed in CH₄–Ar plasma. The dissociation of CH₄ is controlled by changing the mixing position of CH₄ along the Ar plasma produced in a small coaxial tube electrode. When CH₄ is introduced in low electron temperature T_e region, we observed an appearance of nanowires on the surface of microparticles. On the other hand, carbon nanowalls and/or nanoplatelets are formed when the CH₄ is mixed in the high T_e region.     

Tobit model analysis of mutations causing haemophilia

Haemophilia A is a genetic disease resulting from deficiency of factor VIII. The database of mutations causing haemophilia A has been developed by the worldwide collaboration. In this study, we predicted the severity of haemophilia A using ordinary least squares regression (OLS) and Tobit model regression in factor VIII. As parameters, we used four physical–chemical parameters of amino acids and the accessible surface area. As the result, there is a difference between OLS and Tobit model analysis in the prediction of haemophilia A severity. We found that the predicted value by Tobit model in severe data is close to the observed value. These results suggest that Tobit model regression analysis is superior to estimating severity of haemophilia A in severe data than OLS.     

Feasibility Study of a Novel Technique for Measurement of Liquid Thermal Conductivity with a Micro-beam Sensor

A new method was proposed to measure the thermal conductivity of liquids with infinitesimal samples, which are much smaller than those required in conventional methods. The method utilizes a micro-beam-type MEMS sensor fabricated across a trench on a silicon substrate. Numerical analysis of heat conduction within and around a uniformly heated sensor showed that the temperature of a 10 μm long sensor reached a steady state within approximately 0.1ms, after the start of heating. It was also revealed that the average temperature of the sensor at the steady state was higher in liquids with lower thermal conductivity. These results demonstrate a new idea of measuring the thermal conductivity of liquids within an extremely short time at a steady state before the onset of natural convection.     

Breakdown of YBCO thin films during current limiting and methods of improving current limiting performance

We performed fault current limiting tests using YBCO thin films and investigated the reasons for their breakdown during current limiting. There were two patterns of film breakdown. One occurred immediately after current limiting and the other occurred during current limiting. In film breakdown, the quench propagation speed showed almost no change with increasing energy consumption per unit time, but the energy consumption per unit area increased with increasing energy consumption per unit time. Therefore, local areas of the film reached the melting point and arcing occurred. It is therefore concluded that the performance of the films can be improved by decreasing the energy consumption per unit time. Connecting a parallel capacitor to the film in order to limit the energy consumption per unit time is proposed and tested as a measure to improve the current limiting performance of thin films. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(1): 20–27, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20709     

Synthesis and solid-state polymerization of a methylene-chain-modified butadiyne derivative

5,7-Dodecadiyn-1,12-diyl bis[N-(butoxycarbonylmethyl)carbamate] abbreviated as 4BCMU is one of the typical monomers for solid-state polymerization to form polydiacetylene. In this study, we modified 4BCMU by substituting methylene groups to oxygen atoms. Namely, 3,10-dioxa-5,7-dodecadiyn-1,12-diyl bis[N-(butoxycarbonylmethyl)carbamate] (DO-4BCMU) was synthesized and the replacement effects on the monomer properties were investigated. In powder X-ray diffraction experiments, spacings for the layered structure in 4BCMU and DO-4BCMU crystals were found to be 2.74 nm and 3.56 nm, respectively, and large crystal structural difference was confirmed. The polymer absorption maxima of 4BCMU and DO-4BCMU were observed at 630 nm and 580 nm, respectively. Since conversions of these monomers were similar, butadiyne moieties are aligned in polymerizable stacks and the different spacings seemed to be caused by folding structure differences in substituents. We also prepared mixed crystals of 4BCMU and DO-4BCMU with mixing ratio of 3:7 by melt crystal growth. In this crystal, the layered-structure spacing was 2.31 nm, and their similar molecular structures may be responsive for mixed crystal formation with a new phase. However, it was strangely observed that absorption spectrum of the polymer from the mixed crystals corresponded to summation of the spectra of original polymers from 4BCMU and DO-4BCMU.     

Zonotopes and the LP-Newton method

Although linear programming problems can be solved in polynomial time by the ellipsoid method and interior-point algorithms, there still remains a long-standing open problem of devising a strongly polynomial algorithm for linear programming (or of disproving the existence of such an algorithm). The present work is motivated by an attempt toward solving this problem. Linear programming problems can be formulated in terms of a zonotope, a kind of greedy polyhedron, on which linear optimization is made easily. We propose a method, called the LP-Newton method, for linear programming that is based on the zonotope formulation and the minimum-norm-point algorithm of Philip Wolfe. The LP-Newton method is a finite algorithm even for real-number input data with exact arithmetic computations. We show some preliminary computational results to examine the behavior of the LP-Newton method. Major part of this paper was presented as a plenary talk with the same title at ICOTA7 (December 12–15, 2007, Kobe, Japan) by the first author. The fourth author’s research was carried out while visiting RIMS in August 2007.     

Measurement of solid circulation rate in a circulating fluidized bed

A method using an optical mouse sensor was developed to monitor the moving velocity of a solid mass. Calibration was carried out using a rotating plate. Results clarified that the developed method is useful to monitor the velocity up to some limit (v < 0.3 m/s), which depends on the optical mouse sensor used. A solid circulation rate in a circulating fluidized bed (CFB) was measured using this method. Results obtained using this method show agreement with those of visual observations.     

A proposal of port scan detection method based on Packet-In Messages in OpenFlow networks and its evaluation

By quickly detecting a port scan and blocking the culprit host from the network, it is possible to minimize the spread of the damage by infected hosts and malicious users. In the past, various Software-Defined Networking (SDN)-based methods have been proposed, whose main advantage is the lower overhead compared to traditional methods that collect and analyze all captured traffic. On the other hand, due to the polling process used in these methods, it is necessary to set a short interval (e.g., few seconds) to keep the attacks' detection as short as possible. However, when the attack frequency is very low compared to normal traffic, there is an unnecessary overhead. In this paper, we propose a port scan detection method that considers the characteristics of Packet-In messages sent from the OpenFlow (OF) switch to the controller. This allows a prompt detection and with less overhead than conventional polling methods. The evaluation was conducted using both simulated and real traffic data. Results confirm that the proposed method can detect port scans with lower overhead than existing methods.