PREDICTION AND VALIDATION OF EFFECT OF BED LENGTH ON RTD OF COAL IN A BUBBLING FLUIDIZED BED

The residence time distribution (RTD) of coal particles in a bubbling fluidized bed with continuous feeding is calculated with an extended convection-dispersion model, in which segregation of coal is accounted for. The effect of bed length on the RTD of coal is investigated, and the results are validated by experiments

「心拍再開」の内生性を考慮したウツタイン統計データによる救命曲線の推定

本研究では,2008年度と2009年度のウツタイン統計データを用いて,救急活動の時間短縮が心肺停止傷病者の1ヵ月生存確率に与える影響の分析を行うために,「1ヵ月生存」と「心拍再開」からなる2方程式プロビット・モデルを推定し救命曲線の推定を行った.「心拍再開」の内生性を考慮することにより坂本ら[2011]よりも高い再現性を得ることができた

Size distributions of dicarboxylic acids and inorganic ions in atmospheric aerosols collected during polar sunrise in the Canadian high Arctic

Size-segregated atmospheric aerosols (11 stages separating particles from 14.2 μm) collected in the Arctic during the polar sunrise at Alert were analyzed for aerosol mass, dicarboxylic acids, and major inorganic ions. Oxalic, malonic, succinic, and glutaric acids were detected in all size ranges, with oxalic acid being dominant. Their concentrations maximized in the accumulation mode either at 0.24–0.40 or 0.40–0.8 μm aerodynamic diameters, suggesting that diacids were mainly formed by gas-to-particle conversion via photochemical oxidation of nonmethane hydrocarbons and oxygenated organics originated from continental pollution sources. The relative abundances of oxalic acid were higher in the 0.24- to 0.4-μm size particles (73–78%) than in supermicrometer particles (40–60%), indicating that oxalic acid is produced by gas phase oxidation of precursors followed by accumulation on preexisting particles. Mass size distributions of NH4 + and SO4 2− peaked in the accumulation mode similar to those of small diacids. The sea-salt enrichment factor of K+ (biomass burning tracer) relative to Na+ maximized in 0.1- to 0.8-μm sizes, whereas those of Mg2+ and Ca2+ (dust tracers) in 0.4- to 7.8-μm particles. Maximized chlorine loss and bromine enrichment were found at 0.4–0.8 and 0.24–0.4 μm sizes, respectively. Concentrations of Br−, which typically showed a submicrometer maximum, increased significantly during an O3 depletion event having a shift of size distribution to a supermicrometer mode. During this event, oxalic acid concentration relative to succinic acid increased in submicrometer mode (0.24–0.4 μm), adding to a growing body of evidence supporting the hypothesis that halogen chemistry is important in the production and loss of oxalic acid in the arctic atmosphere

Hydroxyl radical-induced photochemical formation of dicarboxylic acids from unsaturated fatty acid (oleic acid) in aqueous solution

In this study, we assess under laboratory controlled conditions the direct and hydroxyl radical (OH)-induced photochemical production of low molecular weight (LMW) dicarboxylic acids and related compounds (C2–C9) (DCAs) from oleic acid (cis-9-octadecenoic, Δ9C18) in aqueous solution. Nitrate (NO3−)-amended and unamended oleate solutions were irradiated under ultraviolet-B radiation (UV-B, 313 nm) for 5 h, with NO3− being the source of OH. The OH-induced photochemical production of DCAs (C2di–C9di) (170 ± 26 nM h−1) was much higher than that induced by the direct effect of UV-B (33 ± 22 nM h−1), accounting for approximately 85% of the total (direct + OH-induced) photochemical production of DCAs (C2di–C9di) (198 ± 15 nM h−1). Azelaic acid (C9di) was the dominant photoproduct (comprising 63 and 44% of DCAs in the direct and OH-induced photochemical production, respectively) followed by C8di, C7di and C6di, whereas shorter chain compounds (C2di–C5di) were minor produced species. Using our estimate of OH photoproduction (P-OH in nM h−1), the production of C9di from 50 μM of oleic acid was evaluated at 45 nM (nM OH)−1

Adaptability verification of scaling law to solid mixing and segregation behavior in bubbling fluidized bed

It is reasonable to speculate the adaptability of Horio's scaling law (equivalent to the simplified Glicksman's scaling law) to the particle mixing and segregation behavior in bubbling fluidized bed (BFB), because the Horio's scaling law is derived from the governing equations of bubbles, and the particle mixing and segregation are dependent on bubble dynamics. In this study, several experiments under various conditions were performed to verify the adaptability of Horio's scaling law. The experimental results indicate that the Horio's scaling law can be successfully applied to mixing and segregation behaviors of Geldart B particles in BFB under the conditions studied in this paper if the scaling relations are strictly satisfied, which is expected to be helpful in the design of fluidized bed reactor. (C) 2012 Elsevier B.V. All rights reserved