A fully pipelined single-precision floating-point unit in the synergistic processor element of a CELL processor

The floating-point unit (FPU) in the synergistic processor element (SPE) of a CELL processor is a fully pipelined 4-way single-instruction multiple-data (SIMD) unit designed to accelerate media and data streaming with 128-bit operands. It supports 32-bit single-precision floating-point and 16-bit integer operands with two different latencies, six-cycle and seven-cycle, with 11 FO4 delay per stage. The FPU optimizes the performance of critical single-precision multiply-add operations. Since exact rounding, exceptions, and de-norm number handling are not important to multimedia applications, IEEE correctness on the single-precision floating-point numbers is sacrificed for performance and simple design. It employs fine-grained clock gating for power saving. The design has 768K transistors in 1.3 mm/sup 2/, fabricated SOI in 90-nm technology. Correct operations have been observed up to 5.6 GHz with 1.4 V and 56/spl deg/C, delivering 44.8 GFlops. Architecture, logic, circuits, and integration are codesigned to meet the performance, power, and area goals.     

Hydrogen generation from a single crystal magnetite coupled galvanically with a carbon steel in sulfate solution

A galvanic coupling with a single crystal magnetite accelerated the corrosion of a carbon steel in sulfate solutions. A scanning electrochemical microscopic investigation revealed that the hydrogen generation on the magnetite as well as the reduction of the magnetite itself was contributed to a galvanic corrosion of the carbon steel. The estimated current efficiency for the hydrogen generation on the magnetite was about 50% in pH 5.8 sulfate solution. Moreover, the distribution of hydrogen generated above the magnetite surface was observed with the probe current image.     

Influences of interfacial recombination on oscillation characteristics of InGaAsP/InP DH lasers

This paper presents the influences of interfacial recombination on the oscillation characteristics of InGaAsP/InP DH lasers. The effects of interfacial recombination at the two InP-InGaAsP interfaces, and a theoretical study of the oscillation characteristics such as threshold current density and differential quantum efficiency are discussed and compared with experimental results. The effects of interfacial recombination on the temperature dependence of threshold current are also examined.     

Effect of electric field on viscoelastic properties of a disperse system in silicone gel

In the electrorheological (ER) fluids of disperse systems, the poor dispersion stability of particles often limits the development of practical application of the fluids. This key problem can be settled by the chemical gelation of ER fluids. In the present study, a dimethylsilicone oil‐based gel containing the nonaqueous ER particles was newly created. The dynamic properties of viscoelasticity in the sample silicone gel were examined under applied DC electric fields of up to 2.0 kV/mm using a sinusoidal oscillating rheometer with low frequencies of 1 Hz or less. The particle behavior and the shearing deformation in the sample gel were also observed using a microscope, a CCD camera, and a color video monitor. When an electric field was applied to the sample gel, the gap between the electrodes was bridged by the chains of particles arranged in the direction of the electric field. Consequently, it is shown that the electroviscoelastic effect of the gel can be controlled by the electric field. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 142(2): 1–9, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10098     

Controlled radical polymerization of N‐isopropylacrylamide initiated by photofunctional 2‐(N,N‐diethyldithiocarbamyl)isobutyric acid sodium salt in aqueous medium

Photopolymerizations of N‐isopropylacrylamide (NIPAAm) were carried out in water, initiated by 2‐(N,N‐diethyldithiocarbamyl)isobutyric acid sodium salt (DTCA‐Na) as water‐soluble initiator under UV irradiation. The first‐order time‐conversion plots showed slowly decreasing slopes indicating a slow decrease of the active radical concentration. The number‐average molecular weight (M_n) of the obtained poly(N‐isopropylacrylamide) (PNIPAAm) increased in direct proportion, roughly, to monomer conversion. Until ca. 60% of conversion, the polydispersity was relatively narrow (ca. 1.6). 1‐Vinyl‐2‐pyrrolidone (VP) could also be polymerized in living fashion with such PNIPAAm precursor as a macroinitiator, because PNIPAAm exhibited dithiocarbamate (DC) groups at terminal ends. It was concluded that the polymerization of NIPAAm proceeded via a controlled radical mechanism in the range ～60% of conversion. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3233–3238, 2004     

Sintering kinetics at constant rates of heating: effect of GeO<Subscript>2</Subscript> addition on the initial sintering stage of 3 mol% Y<Subscript>2</Subscript>O<Subscript>3</Subscript>-doped zirconia powder

The sintering behavior of 3 mol% Y₂O₃-doped zirconia powders with and without a small amount of GeO₂ was investigated to clarify the effect of GeO₂ addition on the initial sintering stage. The shrinkage of powder compact was measured under constant rates of heating (CRH). The sintering rate was accelerated by GeO₂ addition, and increased with increasing GeO₂ content. The mechanism, apparent activation energy (nQ), and apparent frequency factor (β ₀ ⁿ ) of diffusion at the initial sintering stage were estimated using the sintering-rate equations that are applicable to the CRH data. The sintering mechanism changed from grain-boundary (GBD) to volume diffusions (VD) by GeO₂ addition, and both nQ and β ₀ ⁿ of diffusion increased with increasing GeO₂ content. It is, therefore, concluded that the enhanced sintering mechanism by GeO₂ addition is explained by the GBD→VD change and increases in both nQ and β ₀ ⁿ of diffusion at the initial sintering stage.     

Preparation of uniform titania nanocoating on ZnS-based phosphors by a sol–gel process

A sol–gel process has been developed to coat micron-sized ZnS:Cu,Au,Al phosphors with a smooth and uniform layer of amorphous titania having nanosize thickness. The titania nanocoating is based on the hydrolysis and condensation of titanium tetrabutoxide Ti(OBu)₄. Acetylacetone was used to decrease the reactivity of Ti(OBu)₄. The experimental variables such as water concentration, the amount of ZnS particles, and reaction time were investigated. The thickness of the titania nanocoating was homogeneous and can easily be controlled from 20 to 54 nm by adjusting the experimental variables. The as-prepared titania nanocoating was amorphous phase and could be crystallized to anatase phase upon heating at 500 °C in Ar atmosphere.