Transient analysis of the release and reduction of NOx using a Pt/Ba/Al2O3 catalyst

The release and reduction of NO_x in a NO_x storage-reduction (NSR) catalyst were studied with a transient reaction analysis in the millisecond range, which was made possible by the combination of pulsed injection of gases and time resolved time-of-flight mass spectrometry. After an O₂ pulse and a subsequent NO pulse were injected into a pellet of the Pt/Ba/Al₂O₃ catalyst, the time profiles of several gas products, NO, N₂, NH₃ and H₂O, were obtained as a result of the release and reduction of NO_x caused by H₂ injection. Comparing the time profiles in another analysis, which were obtained using a model catalyst consisting of a flat 5 nmPt/Ba(NO₃)₂/cordierite plate, the release and reduction of NO_x on Pt/Ba/Al₂O₃ catalyst that stored NO_x took the following two steps; in the first step NO molecules were released from Ba and in the second step the released NO was reduced into N₂ by H₂ pulse injection. When this H₂ pulse was injected in a large amount, NO was reduced to NH₃ instead of N₂.

A only small amount of H₂O was detected because of the strong affinity for alumina support. We can analyze the NO_x regeneration process to separate two steps of the NO_x release and reduction by a detailed analysis of the time profiles using a two-step reaction model. From the result of the analysis, it is found that the rate constant for NO_x release increased as temperature increase.     

An Application of Silica‐Based Monolithic Membrane Emulsification Technique for Easy and Efficient Preparation of Uniformly Sized Polymer Particles

Summary: Uniformly sized polymer particles were prepared by an emulsification and polymerization technique utilizing a silica monolithic membrane, namely the “silica monolithic membrane emulsification technique”. In this paper, we utilized silica monolithic membrane as a device for the preparation of uniformly sized polymer particles. A mixture of monomers, diluents and oil‐soluble initiator was emulsified into a continuous medium through the silica monolithic membrane and polymerized. The particles obtained had a higher size uniformity than that of particles prepared by previously reported membrane emulsification techniques, such as the Shirasu Porous Glass (SPG) emulsification technique. Through the silica monolithic membrane emulsification technique, we could prepare particles having availability as a possible packing material for solid‐phase extraction (SPE) and high performance liquid chromatography (HPLC).

SEM photograph of silica particles prepared through capillary plate membrane.     

A facile antistatic modification of polyester fiber based on ion-exchange reaction of sulfonate-modified polyester and various cationic surfactants

A new technique for imparting antistatic properties to poly(ethylene terephthalate) (PET) fiber has been developed. In this technique, blend polyester fibers containing poly(ethylene terephthalate/5-sulfoisophthalate) (SIP-PET) were prepared by blend spinning and then treated with various cationic surfactants in the process of dyeing. The surfactants could effectively be immobilized on the fiber as the counter cations of the sulfonate groups of the 5-sulfoisophthalate (SIP) units and aid the release of static electrons formed in the fiber. Thus, the half-life time (t_1/2) of leakage of static charge and the surface resistivity (Rs) of the blend PET fibers became much lower after treating. The best result was obtained with a methylated quaternary ammonium salt of a stearylamine-ethylene oxide (EO) adduct or hydrochloride of a laurylamine-EO adduct as the surfactant of which the number of EO units was around ten. Even after five washing cycles the t_1/2 value of the fibers treated with these surfactants was kept lower than 30 s with the Rs value maintained in the order of 10¹³ Ω cm^-2. Therefore, the present technique could be useful for practical production of polyester fibers with “semi-permanent” antistatic properties which can be recovered by re-treatment even if they were lost.     

Viscoelastic characterization of moderately concentrated polystyrene solutions by dynamic light scattering

The dynamic light scattering measurements were performed for moderately concentrated entangled solutions of atactic polystyrene in benzene (BZ) at 25.0 °C, in cyclohexane (CH) at 34.5 °C (Θ), and in diethyl malonate (DEM) at 35.0 °C (Θ) to characterize their viscoelastic properties. The results have shown that while the mutual diffusion coefficient D increases in the BZ solutions and decreases in the CH and DEM solutions with increasing polymer mass concentration c, the friction coefficient ζ for the three solutions increases with c showing the same power-law behavior irrespective of the weight-average molecular weight M_w and solvent quality. It has been found that the instantaneous longitudinal modulus L₀ for the CH and DEM solutions increases in proportion to c², obeying the familiar relation for the plateau value (4/3)G_N of the longitudinal stress relaxation modulus, but the L₀ values for these solutions are somewhat smaller than the values predicted from the relation. The terminal relaxation time τ_m for the two Θ solvent systems has been found to follow the power-law τ_m∝c^2.7, showing good correspondence to the relation established by rheological measurements.     

Machining accuracy for shearing process of thin-sheet metals—Development of initial tool position adjustment system

In the shearing process, clearance has a significant effect on machining accuracy. However, the relationship between uneven clearance caused by misalignment of tool position and machining accuracy remains unclear. This is attributed to the fact that, previously, the effect was small because the thickness of the workpiece was not so thin, and a method for precisely measuring and adjusting the tool position had not been established. Therefore, in the present study, a new method of adjusting the initial tool position is developed. In addition, punching experiments are conducted under the condition that the initial tool position is adjusted to an accuracy of 2 μm or better, and the effects of clearance on machining accuracy, shape of cross-section, and diameter of hole, are investigated in three types of materials. From these results, the importance of adjusting the initial tool position is clarified.     

High‐pixel‐rate grating‐light‐valve laser projector

Abstract— A high‐pixel‐rate, high‐contrast (30,000:1) wide‐color‐gamut grating‐light‐valve laser projector is reported. A new optical engine enabling high‐frame‐rate (240 Hz) scan projection is employed. Panoramic wide‐angle‐scan projection with a 64:9 aspect ratio was also developed. Speckle noise is eliminated using a simple but highly efficient technique. The optical throughput efficiency of the grating‐light‐valve laser projector is reviewed.     

Integrative Bayesian model on two opposite types of sensory adaptation

Adaptation is a fundamental property of human perception. Recently, it was found that there are two opposite types of adaptation to repetitive stimuli with a temporal difference. In this article, we construct an integrative model of adaptation. We model the perception as a Bayesian inference, and represent the two types of adaptation as changes in the likelihood function and the prior distribution in the Bayesian inference. We examine our model analytically and show how the types of adaptation depend on model parameters.     

Effect of continuous-cooling transformation structure on mechanical properties of 0.4C-Cr-Mo-Ni steel

Commercially available 0.4C-Cr-Mo-Ni steel was studied to determine the effects on its mechanical properties of various microstructures produced by continuous-cooling transformation after austenitization. A good combination of strength and notch toughness was obtained independently of test temperatures (293 and 193 K) when the steel was austenitized at 1173 K and then continuously cooled at an average rate of 3.1 K s^–1 (expressed as the average cooling rate from 823 to 573 K) before final rapid cooling. The microstructure of the steel consisted of a mixed structure of martensite and 10–15 vol% lower bainite, which appeared in acicular form in association with the martensite. Slower cooling had a detrimental effect on the mechanical properties of the steel; the microstructure of this steel consisted of a mixed structure of martensite and upper bainite, which appeared as masses in the matrix. As the average cooling rate increased, the lath size and internal stringer-carbide size in the upper bainite were larger, and retained a somewhat increased austenite content.     

Level-of-Detail Rendering of Large-Scale Irregular Volume Datasets Using Particles

This paper describes a level-of-detail rendering technique for large-scale irregular volume datasets. It is well known that the memory bandwidth consumed by visibility sorting becomes the limiting factor when carrying out volume rendering of such datasets. To develop a sorting-free volume rendering technique, we previously proposed a particle-based technique that generates opaque and emissive particles using a density function constant within an irregular volume cell and projects the particles onto an image plane with sub-pixels. When the density function changes significantly in an irregular volume cell, the cell boundary may become prominent, which can cause blocky noise. When the number of the sub-pixels increases, the required frame buffer tends to be large. To solve this problem, this work proposes a new particle-based volume rendering which generates particles using metropolis sampling and renders the particles using the ensemble average. To confirm the effectiveness of this method, we applied our proposed technique to several irregular volume datasets, with the result that the ensemble average outperforms the sub-pixel average in computational complexity and memory usage. In addition, the ensemble average technique allowed us to implement a level of detail in the interactive rendering of a 71-million-cell hexahedral volume dataset and a 26-million-cell quadratic tetrahedral volume dataset.     

Particle-based multiple irregular volume rendering on CUDA

In this paper, we describe an improved particle-based volume rendering (PBVR) technique for previewing a large irregular volume dataset using the CUDA architecture. This technique allows for opaque and emissive particles to render translucent volumes without visibility sorting. Our GPU acceleration of PBVR provides the multi-volume rendering feature while remaining compatible with both regular and irregular volumes. We also reduce the memory cost required for storing all sub-pixel values by proposing a pixel repetition technique for a large sub-pixel level. By adjusting the repetition level, we achieved a very smooth level of detail (LOD) control for trading quality for speed. Our work demonstrates a full-detail rendering rate from 5 to 10 fps for irregular volume data with mega-scale cell numbers on an NVIDIA GeForce 8800GTS.