Numerical analysis of the effect of boundary layer thickness on vortex structures and heat transfer in the wake behind a hill

This study presents a three‐dimensional numerical analysis of the effect of boundary layer thickness on vortex structures and heat transfer behind a hill mounted in a laminar boundary layer. When the thickness of the velocity boundary layer is comparable to the hill height, a hairpin vortex is formed symmetrically to the center of the spanwise direction in the wake. A secondary vortex is formed between the legs, and horn‐shaped secondary vortices appear under the concave parts of the hairpin vortex. When the boundary layer thickness increases, the legs and horn‐shaped secondary vortices move toward the center of the spanwise direction, and thus heat transport and heat transfer increase there. At this time, high‐turbulence areas generated locally move toward the center of the spanwise direction with an increase in the boundary layer thickness. With a further increase in the boundary layer thickness, steady streamwise vortices are formed downstream of the hill, but the heat transfer decreases. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20261     

Expression of aldehyde dehydrogenase gene increases hydrogen production from low concentration of acetate by Rhodobacter sphaeroides

Rhodobacter sphaeroides RV (RV) is a hydrogen-producing bacterium exhibiting the highest yield of hydrogen production from organic acids such as lactate and acetate, which are the byproducts of hydrogen fermentation by hydrogen-producing anaerobic bacteria. Co-fermentation of the RV strain with anaerobic bacteria is an efficient method of hydrogen production. However, less than 21 mM acetate is produced by the anaerobic bacteria, which is too low for efficient hydrogen production by the RV strain; it requires approximately 75 mM acetate. In this study, 2 distinct isozymes of aldehyde dehydrogenase from Rhodospirillum rubrum were separately overexpressed in the RV strain. The recombinant RV strains that were designated as RVAD1 and RVAD2, exhibited 13-fold higher ALDH activities than the wild-type RV strain. Hydrogen yields of both of the recombinant strains were 1.4-fold higher than that of the RV strain in 21 mM acetate. In 43 mM acetate, the RVAD1 strain showed higher yield, though the RVAD2 strain showed lower yield as compared to that of the RV strain. In 64 mM acetate and all concentrations of lactate tested (21, 43 and 64 mM), the yields of the recombinant strains were lower than those of the RV strain. The intact (empty) expression plasmid increased the ALDH activity and had little effect on the hydrogen production in acetate, however, it decreased the production in lactate. At the beginning of the fermentation process, when very little hydrogen had been produced, the recombinant strains expressing the ALDH gene consumed smaller amounts of acetate compared to the wild-type strain. We have discussed the effects of ALDH on hydrogen production in this report.     

Pseudomonas spp. convert metmyoglobin into deoxymyoglobin

Meat ‘reddening’ by bacteria was observed in chilled beef. To identify the reddening bacteria, isolates were inoculated onto beef and the changes in CIE L^*a^*b^* values monitored. As a result, two Pseudomonas spp., including Pseudomonas fragi which is commonly observed in raw meat, were selected and identified as reddening bacteria. The reddening was coincidentally occurred with the appearance of slime, and the increase in thiobarbituric acid-reactive substances (TBARS) was simultaneously suppressed. In myoglobin-containing nutrient broth, it is shown spectroscopically that P. fragi converted metmyoglobin into deoxymyoglobin. It was concluded that the meat reddening was due to the formation of deoxymyoglobin, induced by the very-low-oxygen tension brought about by Pseudomonad’s oxygen consumption: This oxygen depletion simultaneously suppressed TBARS increase.     

Empirical study on the environmental Kuznets curve for CO2 in France: The role of nuclear energy

This paper attempts to estimate the environmental Kuznets curve (EKC) in the case of France by taking the role of nuclear energy in electricity production into account. We adopt the autoregressive distributed lag (ARDL) approach to cointegration as the estimation method. Additionally, we examine the stability of the estimated models and investigate the Granger causality relationships between the variables in the system. The results from our estimation provide evidence supporting the EKC hypothesis, and the estimated models are shown to be stable over the sample period. The uni-direction running from other variables to CO₂ emissions are confirmed from the casualty tests. Specifically, the uni-directional causality relationship running from nuclear energy to CO₂ emissions statistically provides evidence on the important role of nuclear energy in reducing CO₂ emissions.     

Precise metabolic flux analysis of coryneform bacteria by gas chromatography-mass spectrometry and verification by nuclear magnetic resonance

Precise metabolic flux analysis (MFA) by gas chromatography-mass spectrometry (GC-MS) and computer calculation was performed, and the consistency of the estimated results was verified by independently performed nuclear magnetic resonance (NMR) analysis. The precise estimation of flux by the integration method of the mass isotopomer signal, defined as the coefficient of variance (CV) of multiple determination, was investigated, and the results estimated using different data sets with the same magnitude of error were confirmed. The CV of multiple determinations was sufficiently small to discuss and compare the fluxes of a metabolic pathway. The estimated fluxes using the GC-MS data were cross-validated with the NMR data that were independently measured and not used for MFA. The developed method was successfully applied to the MFA of the growth phase of two different glutamate-producing coryneform bacteria, Corynebacterium glutamicum and C. efficiens. The difference in the growth rate between these two bacterial species was discussed while considering the results of MFA, including forward and backward (exchange) fluxes.     

Flow structure and heat transfer mechanism of laminar vortex rolls driven by gravity currents between parallel plates of nonuniform wall temperature

Laminar vortex rolls which occur between horizontal parallel plates, of which the temperature is not uniform in the lateral direction normal to the forced main flow, are investigated by means of a flow-visualization technique and a 3D steady-state numerical calculation. It was found that the vortex rolls were driven by the horizontal gravity currents, which were caused by density difference in the lateral direction, and that the generation mechanism of the vortex rolls could be classified into four types. The effects of vortex rolls on the local Nusselt number were also investigated. © 1999 Scripta Technica, Heat Trans Asian Res, 28(7): 606–619, 1999     

The Application of VDM to the Industrial Development of Firmware for a Smart Card IC Chip

We have applied the formal speci.cation language in the development of the .rmware of the smart card IC chip for embedding in mobile phone. We report on an in-dustrial application of formal methods to the development of a complex system, namely the .rmware for the “Mobile FeliCa” smart card IC chip. The use of formal techniques, specif-ically the Vienna Development Method (VDM), was aimed at raising the quality of system speci.cations by reducing ambiguity and improving communications between engineers. De-velopment data gathered during the life cycle con.rm the e.ectiveness of a lightweight formal method in contributing to the quality of the deliverables in early development stages. No software speci.cation problems have, to date, been reported since .rst release (over 100 million mobile phones have the chip embedded).     

A spatial evaluation of forest biomass usage using GIS

We conducted a spatial evaluation of forest biomass usage using a geographic information system (GIS) for the Japanese town of Yusuhara. In Japan, over 60% of the land is covered with forest, of which at least 40% is artificial forest. However, because of high labor costs, the profitability of forestry is decreasing, so timber cultivation is not done to the extent that it could be, and thinning has to be subsidized. Under these circumstances, much of the forest is deteriorating. Most of the thinning is accounted for by throwaway thinning, in which the resulting wood is not used. However, with the steep rise in oil prices and the intensification of global warming concerns, expectations are rising for the use of biomass energy from thinned timber that has previously been discarded. If thinned timber, logging residues, and offcuts are utilized for biomass energy and their economic value becomes apparent, profitability will improve for both final cutting and thinning. And in addition to forestry activities being invigorated, it will be possible for some of the deteriorating forests (which have associated dangers such as landslides) to recover. However, using thinned timber and logging residues is problematic in that profitability is affected by harvesting costs. Harvesting costs are largely determined by geographic factors and are higher for more distant stands. Accordingly, in this article, operational costs for different stands are calculated using GIS and matched with total demand in the subject region. In addition, stands with lower operational costs are identified and an investigation of a highly feasible use of forest biomass is carried out.     

High-efficiency InGaP/In0.01Ga0.99As tandem solar cells lattice-matched to Ge substrates

Conversion efficiency (AM1.5G) of more than 30% was achieved by adding a small quantity of Indium into a GaAs bottom cell in the conventional tandem solar cell on Ge substrate. It was found that the lattice-mismatch between GaAs and Ge caused misfit-dislocations in thick GaAs layers and reduced an open-circuit voltage (V_oc) of the cell. An In_0.49Ga_0.51P/In_0.01Ga_0.99As tandem cell lattice-matched to Ge showed a great improvement in efficiency, which was attributed to an increase in the V_oc of the bottom cell and increases in the photocurrents both in the top and bottom cells due to reductions in band-gap energy.     

Polymer-electrolyte water electrolysis

The electricity for the electrolyzer is supplied by a variable electricity supply unit that simulates actual outputs of both series and parallel combinations of solar cells exposed to various solar intensities. An amorphous-silicon solar cell is used as a sensor for the unit The operation was continued for more than 600 days without trouble. The case of direct connection of the solar cell and polymer electrolyte (PE) water electrolyzer is simulated: the test results show that more than 95% of the peak electricity power of the solar battery can be utilized for the electrolyzer over various solar radiation conditions.