Detection and modification of confusing color combinations for red‐green dichromats to achieve a color universal design

Color‐vision deficiency is a relatively common genetic condition, which often leads to the obstruction of necessary information in colored images. It is important to minimize such inconvenient effects in communication using colored images from a universal design perspective. The universal design principle stipulates that all environments and products should be usable by all people, regardless of age, physical attributes, and ability. This article proposes a method to detect color combinations in a given image that would confuse color dichromats, and suggests a way in which to modify them to make the image easily distinguishable for both normal and dichromatic observers. Confusing color combinations were detected based on a color‐difference calculation using simulations of how the color would appear to dichromats. The confusing colors were then modified based on the minimization of an evaluation function, which was defined as the sum of the degree of confusion and the degree of color change from the original image. Several colored images obtained by the proposed method were compared with the originals by red–green dichromatic observers who judged them to be clearer, thereby confirming that the proposed method was effective for color rendering for universal design. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 203–211, 2008     

Efficient electron transport in 4,4′-bis[N-(1-napthyl)-N-phenyl-amino] biphenyl and the applications in white organic light emitting devices

The electron transport capability of 4,4′-bis[N-(1-napthyl)-N-phenyl-amino] biphenyl (α-NPD) was investigated by fundamental physical measurements named as current–voltage (I–V) electrical property evaluation and displacement current measurement (DCM). In electron-dominated devices, the I–V characteristics of α-NPD were similar as that of (8-hydroxyquinolino) aluminum (Alq₃) owing to their same order of electron mobilities. The interface of Al/LiF and α-NPD was proven to be an Ohmic contact through the evaluation of I–V characteristics at low bias regime (<3 V). And an electron injection barrier, 0.21 eV, at Al/LiF/α-NPD was obtained by extrapolating the temperature dependent I–V curves. The electron transport behavior in α-NPD film was further confirmed by DCM evaluations. Furthermore, an efficient white organic light emission device was successfully fabricated by using α-NPD as hole transport layer and electron transport layer, respectively.     

A promising application for broadband ISDN: Hypermedia teleconference

The optimum BISDN teleconference service for business, called hypermedia teleconference, is designed based on research into typical business activities and ATM, the most promising BISDN architecture. Service characteristics are determined by analysing the daily work practices of a large set of businessmen. It is shown that communication tasks occupy 44 per cent of the working day. The analysis further shows that some 60 per cent of all communication tasks could be performed through an advanced digital teleconference service. Hypermedia teleconference is designed to satisfy the needs of business through personal communication terminals and ATM public networks. The terminals effectively allocate the BISDN's high-speed transmission capability between a number of subchannels that realize distributed multipoint connection links and multimedia paths. The terminals use a new variable-bit-rate ATM codec created to realize high quality video. Users can easily create full featured teleconferences without a centralized connection facility. Terminals allow the synergistic combination of video, voice, telewriting, telepointing and document transmission services.     

1千伏以下的金属球间隙静电放电辐射特性的测量研究

In this study, the characteristics of Electromagnetic (EM) radiation caused by Electrostatic Discharges (ESDs) from metal spheres charged to voltages less than 1 kV are examined experimentally. Our experimental system consists of a pair of spherical elec-trodes of different diameters, a 1-18 GHz-band- width horn antenna and a 20-GHz-bandwidth digitizing oscilloscope. Polarization, waveform duration and peaks of antenna-received voltages from the EM field radiation are measured in order to clarify the EM radiation mechanism. The ratio of the received voltages between the antenna arr-angements of the field polarization parallel and perpendicular to the spark pass is 18 to 20 dB. The polarities of the antenna-received voltages are the same as those of the charge voltages across the gap. Moreover, the waveform duration and the first peaks increase with an increase in the diameters of the spherical electrodes. Consequently, we find that the polarization, waveform duration and first peaks of the EM field radiation can be explained by a dipole antenna structure, which makes the spark part of the spherical electrodes a feeding point on the straight line passing through the centres of the two spheres.     

Dual-Mode Space-Temporal Simultaneous Processing Equalizer

A tapped delayed line adaptive array antenna (TDL-AAA) and a space-temporal simultaneous processing equalizer (ST-SPE) are proposed as simple space-temporal equalizers based on minimum mean square error (MMSE) criterion. The ST-SPE has a compact hardware with a small number of taps compared to that of the TDL-AAA. The ST-SPE can reduce the computational complexity of the space-temporal joint equalization and it works effectively under the minimum phase condition such as appeared at line-of-sight (LOS) propagation environments at a high antenna height base station. However the ST-SPE cannot work under a non-minimum phase condition caused under N-LOS (non-line-of-sight). On the other hand, the TDL-AAA whose reference signal is synchronized at the center tap (TDL-AAA_C) can work even in the non-minimum phase condition. In this paper, we propose a dual-mode space-temporal simultaneous processing equalizer (Dual-mode ST-SPE) which has a simple configuration and also works in non-minimum phase condition. The Dual-mode ST-SPE can reduce the computational complexity compared to the TDL-AAA_C. Yoshihiro Ichikawa received the B.E. degree in department of communication engineering, in National Defense Academy in 1995, and M.E. and D.E. degree from Ibaraki University in 2001 and 2004, respectively. He joined the Japan Air Self Defense Force in 1995. His research interests are an adaptive algorithm, an antenna design, and an adaptive array antenna. Shigeki Obote received his B.E., M.E. and D.E. degrees in electrical and electronic engineering from Tottori University, Tottori, Japan, in 1996, 1998 and 2000, respectively. Since 2000, he has been with department of media and telecommunications engineering, faculty of engineering, Ibaraki University, Ibaraki, Japan, where he is currently a associate professor. His research interests are in adaptive array antenna and wireless communications systems. Kenichi Kagoshima received the B.E., M.E. and D.E. degrees in electronics engineering from the Tokyo Institute of Technology, Tokyo, Japan, in 1969, 1971, and 1974, respectively. He joined the Nippon Telegraph and Telephone Corporation (NTT) Laboratory in 1974 and researched and developed many kinds of radio communication antennas. Since 1997, he has been a professor at Ibaraki University, Ibaraki, Japan. Dr. Kagoshima was a Secretary and Treasure, Vice Chairman, and Chairman of the IEEE AP-S Tokyo Chapter in 1992, 1993, and 1994, respectively. He was a chair of antennas and propagation professional group of IEICE in 1999 and 2000. In 1973, he received the Yonezawa Prize for Young Engineers and 1998, best paper award from IEICE, respectively.     

Improved efficiency of Al0.36Ga0.64As solar cells with a ppnn structure

Improvement of efficiency of Al_0.36Ga_0.64As solar cells is advanced in two aspects of minority-carrier lifetime: reduction of majority-carrier concentration in the emitter and base layers, and reduction of deep levels in the back-surface-field (BSF) layer. A pp⁻n⁻n structure is proposed to optimize the use of the effect of reduced majority-carrier concentration, and its effectiveness verified in a preparatory experiment on Al_0.3Ga_0.7As solar cells. A very poor photoluminescence (PL) decay time (below 0.3 ns) of a BSF layer heavily doped with Si becomes 14-fold longer when Se is applied to the dopant instead of Si, resulting in an improvement of the external quantum efficiency near the absorption edge. These two aspects of this study lead to the realization of 16.6% efficiency under 1-sun, AM 1.5 global conditions with an Al_0.36Ga_0.64As solar cell.     

Risk assessment of Hydrogen fueling stations for 70 MPa FCVs

People are placing their hopes on the future of fuel-cell vehicles (FCVs) to replace today's gasoline-fueled vehicles. To encourage the widespread use of FCVs, however, these vehicles must be able to drive a distance of at least 500 km, mileage comparable to today's gasoline-fueled vehicles. To achieve this distance, automobile manufacturers are focusing their efforts on developing new hydrogen fuel tanks that will raise pressure to 70 MPa from the current 35 MPa. At the same time, hydrogen stations will also have to be able to provide 70 MPa compressed hydrogen gas to service these improved FCVs. Regulations for hydrogen fueling stations where pressure is no higher than 40 MPa were established in 2005 in Japan but it goes without saying that these regulations are inadequate for hydrogen fueling stations of 70 MPa.     

Chemospecific ring-opening polymerization of α-methylenemacrolides

α-Methylenemacrolides having various groups, such as aromatic, ether, and amine, were enzymatically, anionically, and radically polymerized. The polymerization with the lipase catalyst successfully afforded polymers only through the ring-opening process, whereas the vinyl polymerizations selectively proceeded by using anionic and radical initiators. The polyesters obtained by the enzymatic polymerization have a polymerizable methacrylic methylene group in the main-chain, in addition to the aromatic and polar groups, and were further radically polymerized to quantitatively produce a cross-linked polymer gel.     

Diffusion process of amino acids in polymer supports for solid‐phase peptide synthesis as studied by pulsed‐field‐gradient spin‐echo proton nuclear magnetic resonance

The diffusion coefficient (D) values of tert‐butyloxycarbonyl‐glycine, tert‐butyloxycarbonyl‐L ‐tryptophan, tert‐butyloxycarbonyl‐L ‐phenylalanine (Boc‐Phe), and 9‐fluorenylmethoxycarbonyl‐L ‐phenylalanine in Merrifield polystyrene (MPS) gels, poly(ethylene glycol)‐grafted polystyrene (PEG–PS) gels, and crosslinked ethoxylate acrylate (CLEAR) gels, as used in solid‐phase peptide synthesis, were determined by the pulsed‐field‐gradient spin‐echo ¹H‐NMR method. From these experimental results, it was found that the amino acids in MPS gels, PEG–PS gels, and CLEAR gels with N,N‐dimethylformamide‐d₇ (DMF‐d₇) as a solvent had multidiffusion components within a measurement timescale of 10 ms. The D value of Boc‐Phe in polystyrene gels (1% divinylbenzene crosslinked) with tetrahydrofuran‐d₈ was much larger than that in the same gels with DMF‐d₇. Furthermore, the required time in which an amino acid transferred from a reactive site to a reactive site was estimated, within which the solvents and amino acids in the polymer supports diffused in the swollen beads.© 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 413–421, 2003     

Residual stress versus microstructural effects on the strength and toughness of phase-separated PbO–B2O3–Al2O3 glasses

A few authors have reasonably proposed that liquid–liquid phase-separated (LLPS) glasses could show improved fracture strength, S_f, and toughness, K_Ic, as the second phase could provide a barrier to crack propagation via deflection, bowing, trapping, or bridging. Due to the associated tensile or compressive residual stresses, the second phase could also act as a toughening or a weakening mechanism. In this work, we investigated five glasses of the PbO–B₂O₃–Al₂O₃ system spanning across the miscibility gap: Four of them undergo LLPS—three are binodal (two B₂O₃-rich and one PbO-rich) and one is spinodal—and one does not show LLPS (composition outside the miscibility gap). Their compositions were designed in such a way that the amorphous particles are under compressive residual stresses in some and under tensile residual stresses in others. The following mechanical properties were determined: the Vickers hardness, ball on three balls (B3B) strength, and toughness, K_Ic-SEVNB (single-edge V-notch beam [SEVNB]). The microstructures and compositions were analyzed using scanning electron microscopy with energy-dispersive X-ray spectrometry. The spinodal glass showed, by far, the best mechanical properties. Its K_Ic-SEVNB = 1.6 ± 0.1 MPa m^1/2, which embodies an increase of almost 50% over the B₂O₃-rich binodal composition, and 90% considering the PbO-rich binodal composition. Moreover, its fracture strength, S_f = 166 ± 7 MPa, is one of the highest ones ever reported for an LLPS glass. Fracture analyses evidenced that the spinodal composition exhibited the lowest net stress at the fracture point. Moreover, calculations indicate that the internal residual stress level is the lowest in the spinodal glass. The overall results indicate that the microstructural effect of the spinodal glass is the most significant factor for its superior mechanical properties. This work corroborates the idea that LLPS provides a feasible and stimulating solution to improve the mechanical properties of glasses.