Stress analysis method considering piezoelectric effects and itsapplication to static strain optic devices

A stress analysis method considering piezoelectric effects based on the finite-element method (FEM), which can be applied to arbitrarily anisotropic material-based optical waveguide devices, is newly formulated. To produce a two-step analysis of static strain optic (SSO) and electrooptic (EO) modulations of optical waveguide devices, this stress analysis is linked to the guided mode analysis and the beam propagation analysis taking into account the refractive index changes. Numerical examples are shown for strain-induced optical waveguides and strain-induced polarization mode converters on LiNbO₃ substrates     

A 53° twisted-nematic cell for a color reflective liquid-crystal display

Abstract— A 53° twisted-nematic cell for a color reflective liquid-crystal display was developed. It has a mirror electrode inside the panel on the TFT substrate, a twisted-nematic alignment structure, an RGB color filter, a single polarizer, and a light-control film covering the panel. Its advantages include gray-scale capability, low driving voltage, and a wide viewing angle. We discuss the Δn?d, the twist angle, and the front-light control film.     

Separation of aqueous phenol through polyurethane membranes by pervaporation. II. Influence of diisocyanate and diol compounds and crosslinker

The influence of diisocyanate and diol compounds of polyurethane and crosslinking agent on the separation of phenol aqueous solution by pervaporation was investigated. Polyurethanes were prepared by polyaddition of diisocyanate and diol compounds and trimethylolpropane (TMP) using dibutyltindilaulate as a catalyst. The polyurethane membrane was prepared by a casting method and was sandwiched with a porous polypropylene membrane (Celgard® 2500). Pervaporation measurement was carried out under vacuum on the permeate side, and the permeant was collected with a liquid nitrogen trap. Little influence of diisocyanate compounds on the phenol permselectivity through diisocyanate–polytetramethyleneglycol [PTMG(1000)] membranes was observed since the influence on the solubility and the diffusivity was small. The phenol permselectivity was increased with an increase in the molecular weight of PTMG and polycaprolactone diol (PCL) for the 1,6‐diisocyanato hexane (HMDI)–PTMG and HMDI–PCL membranes. It was considered that the increase in phenol diffusivity can be attributed to an increase in phenol selectivity. The permeability and selectivity of HMDI–[PTMG(2900)–TMP] membrane was relatively constant below the 2% TMP content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 439–448, 1999     

Improved design of a three‐dimensional,static concentrator lens using meteorological data

A three‐dimensional, rectangular concentrator lens (3D lens) has been designed by combining two kinds of two‐dimensional compound elliptic lenses and meteorological data. Optical concentration ratios of the 3D lenses designed at various half‐acceptance angles are calculated and measured as a function of light incidence angle. Yearly integrated irradiance and yearly averaged module efficiency are simulated using the calculated optical concentration ratios and meteorological data. A performance index—a product of entry aperture and cell occupation ratios—is defined to compare with that of flat‐plate modules. Consequently, designed half‐acceptance angles are optimized at 40° and 70° in north–south and east–west directions. The occupation area of solar cells can be reduced to 62% using this lens although module area increases to only 1·16 times that of the flat‐plate module. Copyright © 1999 John Wiley & Sons, Ltd.     

A translucent display algorithm for G-octree represented grey-scale images

A new translucent display algorithm is proposed for grey-scale images represented by G-octrees. The algorithm generates a special triangle quadtree as the display image for the isometric projection of a G-octree, while traversing the G-octree from front to back, with respect to the viewpoint. A method of using the translucent effect to analyse the interiors of three-dimensional objects is also described, together with its implementation results.     

Recent progress in research and development of crystalline silicon solar cells in Japan

Recently, the research and development of crystalline silicon solar cells in Japan has greatly advanced. Fundamental research has been conducted on the recombination and passivation of minority carriers at Si/SiO₂ interfaces and in those bulk regions containing grain boundaries. Qualities of silicon feedstock and substrates have been improved and large-area cell efficiencies using Czochralski single and cast polycrystalline substrates have reached 20% and 17%, respectively, by using low-cost cell fabrication processes. Such high efficiency values are realized by tenacious improvement of substrate quality and the development of new processes for fabricating solar cells.     

Analysis and measurement of the effect of kernel locks in SMP systems

This article reports the use of case studies to evaluate the performance degradation caused by the kernel-level lock. We define the lock ratio as a ratio of the execution time for critical sections to the total execution time of a parallel program. The kernel-level lock ratio determines how effective programs work on symmetric multiprocessor (SMP) systems. We have measured the lock ratios and the performance of three types of parallel programs on SMP systems with Linux 2.0: matrix multiplication, parallel make, and WWW server programs. Experimental results show that the higher the lock ratio of parallel programs, the worse their performance becomes. Copyright © 2001 John Wiley & Sons, Ltd.     

Melt-quenched oxide glasses with ultrahigh Young's modulus and small thermal expansion coefficient

The well-known Makishima–Mackenzie relationship, consisting of two terms of the dense packing structure and dissociation energy regarding bonding in constituent oxides, enables fabricating oxide glasses with ultrahigh Young's modulus (∼140 GPa) and a small coefficient of thermal expansion (CTE) (∼4 ppm/K). The effects of increasing MgO and Ta₂O₅ contents in an MgO–Ta₂O₅–Al₂O₃–SiO₂–B₂O₃ glass system using a conventional melt-quenching method are revealed. The essential oxides of Al₂O₃ and Ta₂O₅ are primarily suitable for dense packing structures dominated by a large coordination number of oxygens. The substitution of CaO by MgO results in high dissociation energy when the glass composition falls in the peraluminous regime (Al₂O₃/[MgO + CaO] > 1). A small CTE is realized by increasing the molar ratio of Al₂O₃/MgO. According to magic-angle spinning-nuclear magnetic resonance spectra, mechanically and thermally functional oxide glasses depend on their structures. These findings facilitate the development of glass substrate applications without thermal dilatation.