Multiple stack performance near saturation

Detailed simulation experiments have been performed to study multiple stack performance, primarily using two methods recently developed by the authors called dynamic initial allocation and local reallocation procedures. Some results are: determining first occurrences of overflows in terms of storage saturation; observing performance behaviours, particularly for near full storage saturation; and performance evaluation on the weight of two storage redistribution schemes, one being based on the most recent stack growth, the other on the current stack size. Also discussed is the issue of whether additional space should be sought when storage is near saturation, and if so, how it is to be obtained. The critical stack saturation percentage is proposed as the point where additional storage space should be sought. It is the one at which the expected total cost is the minimum.     

Production of monodispersed water-in-oil emulsions using polymer microchannels

Monodispersed water-in-oil (W/O) emulsions were prepared using new fabricated acrylic polymer microchannel (MC) plates. Acrylic plate MC-A1 was 20 μm wide, 10 μm deep, and 120 μm long; and MC-A2 was 40 μm wide, 20 μm deep, and 120 μm long with respect to MC sizes. Both MC plates had a terrace length of 30 μm. Monodispersed waterin-triolein emulsions with average diameters of 42 to 60 μm (MC-A1) and 62 to 98 μm (MC-A2) were prepared successfully using tetraglycerin condensed ricinoleic acid ester (CR310) as a surfactant. The CV for droplets produced was less than 10%, demonstrating monodispersity. When we used decane (which is less viscous than triolein) as the continuous phase and CR310 and hexaglycerin pentaoleate (PO500) as surfactants, the average diameters and CV of the droplets became smaller, and the pressure ranges for stable droplet formation were much wider than for the water/triolein system. For comparison, a silicon MC plate (MC-Si) with dimensions similar to the polymer MC-A1 was tested and exhibited little significant difference in the average diameter and CV of droplets between MC-A1 and MC-Si.     

Control strategy of leveling load power fluctuations based on fuzzy neural networks by tuning coefficients of learning rate with genetic algorithm

The effective usage of the power facilities can be realized by leveling the fluctuating active power and compensating the reactive power. The fuzzy and fuzzy neural network control strategy of superconducting magnetic energy storages (SMES) was proposed for this purpose. The control results depend on the values of coefficients of learning rate in fuzzy neural networks. Therefore, it is desirable to obtain better control results by tuning the coefficients of learning rate to their optimum values. In this paper, the control strategy based on an autotuning of scaling factors with neural network and tuning of coefficients of learning rate of neural network with genetic algorithm is proposed for leveling load fluctuations. Encoding and decoding of coefficients of learning rate and selection, crossover, and mutation within genetic operations are shown, and crossover rate and mutation rate are discussed. Through these methods, we can achieve a better leveling of load power fluctuation by using fuzzy neural network with genetic algorithm. © 1998 Scripta Technica, Electr Eng Jpn, 125(1): 65–72, 1998     

Preparation and gas permeation of immobilized fullerene membranes

Fullerene‐dispersed membranes were homogeneously prepared under the conditions in which a 10 wt % polystyrene solution containing 1 wt % fullerene was dried under a reduced pressure of 50 cmHg at room temperature. The fullerene membranes prepared with 1,2‐dichlorobenzene were found to have the darkest color, and showed no evidence of fullerene crystals in their photomicrographs. UV‐visible and infrared absorption spectra of the fullerene membranes showed fullerene bands, which indicated that the fullerene was homogeneously dispersed in the membranes. The permeability coefficients of pure nitrogen, oxygen, carbon dioxide, ethane, and ethylene were found to increase significantly in the fullerene membranes compared to those in the polystyrene membranes, although the ideal separation factors for oxygen/nitrogen and ethylene/ethane in the fullerene membranes (i.e., 4.3 and 1.7, respectively) were slightly less than the separation factors in the polystyrene membranes. The permeability increase originated from the increase in diffusion coefficients in the fullerene membranes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 529–537, 2000     

Arsenic adsorption from aqueous solution on synthetic zeolites

The adsorption of arsenic from aqueous solution on synthetic zeolites H-MFI-24 (H24) and H-MFI-90 (H90) with MFI topology has been investigated at room temperature (r.t) applying batch equilibrium techniques. The influences of different sorption parameters such as contact time, solution pH, initial arsenic concentration and temperature were also studied thoroughly in order to optimize the reaction conditions. The adsorption of arsenic on to H24 and H90 follows the first-order kinetics and equilibrium time was about 100min for both the adsorbents. The first-order rate constant (k), 4.7 x 10(-3)min(-1) for H90 is more than two times higher in magnitude compared to 2.1 x 10(-3)min(-1) for H24. Adsorption performance of H90 is higher compared to H24 due to it's highly mesoporous nature which in turn accelerates the diffusion process during adsorption. As(V) sorption capacity derived from Langmuir isotherm for H24 and H90 are 0.0358 and 0.0348gg(-1), respectively. Arsenic uptake was also quantitatively evaluated using the Freundlich and Dubinin-Kaganer-Radushkevich (DKR) isotherm models. Ion exchange between adsorbent's terminal aluminol groups with different predominant forms of arsenate in solution is one of the various important reactions occurred during adsorption process.     

Hydrogen Permeation Properties and Hydrothermal Stability of Sol–Gel‐Derived Amorphous Silica Membranes Fabricated at High Temperatures

The sol–gel method was applied to the fabrication of amorphous silica membranes for use in hydrogen separation at high temperatures. The effects of fabrication temperature on the hydrogen permeation properties and the hydrothermal stability of amorphous silica membranes were evaluated. A thin continuous silica separation layer (thickness = <300 nm) was successfully formed on the top of a deposited colloidal silica layer in a porous glass support. After heat treatment at 800°C for an amorphous silica membrane fabricated at 550°C, however, it was quite difficult to distinguish the active separation layer from the deposited colloidal silica layer in a porous glass support, due to the adhesion of colloidal silica caused by sintering at high temperatures. The amorphous silica membranes fabricated at 700°C were relatively stable under steam atmosphere (500°C, steam = 70 kPa), and showed steady He and H₂ permeance values of 4.0 × 10^?7 and 1.0 × 10^?7 mol·m^?2·s^?1·Pa^?1 with H₂/CH₄ and H₂/H₂O permeance ratios of ~110 and 22, respectively. The permeance ratios of H₂/H₂O for membranes fired at 700°C increased drastically over the range of He/H₂ permeance ratios by factors of ~3–4, and showed a value of ~30, which was higher than those fired at 500°C. Less permeation of water vapor through amorphous silica membranes fabricated at high temperatures can be ascribed to the dense amorphous silica structure caused by the condensation reaction of silanol groups.     

Production of -aminobutyric acid (GABA) by Lactobacillus paracasei isolated from traditional fermented foods

Lactobacillus strains that accumulated γ-aminobutyric acid (GABA) in culture medium were screened to determine strains with high GABA-producing ability. One strain, NFRI 7415, which was isolated from a Japanese traditional fermented fish (funa-sushi), showed the highest GABA-producing ability among the screened strains. Identification tests (i.e., 16S rDNA sequencing and sugar assimilation ability) indicated that NFRI 7415 belongs to Lb. paracasei. The GABA production was further improved by the addition of pyridoxal phosphate to the culture medium and pH regulation of culture medium at pH 5.0. Under optimal cultivation conditions, strain NFRI 7415 produced GABA at a concentration of 302 mm when the glutamate concentration in the culture medium was 500 mm.     

Bounding Surface Model for Geosynthetic Reinforcements

Geosynthetic reinforcements are manufactured from polymers such as polyester, polypropylene, and high-density polyethylene. Compared to metals, they exhibit large plastic strains, and highly nonlinear and hysteretic behaviors under cyclic loading. Most geosynthetic reinforcements do not sustain compression load. Traditional cyclic models with the Masing rule fail to simulate such unique behavior. A 1D bounding surface concept is used to develop a model that considers these unique properties of geogrids. The unique features of the model include nonparallel bounding lines and different loading and unloading hardening parameters. The model was calibrated and compared with the experimental results of two geogrids under monotonic and cyclic loadings with different load amplitudes.