Effects of oxygen supply condition and specific biofilm interfacial area on phenol removal rate in a three‐phase fluidized bed bioreactor

The effects of oxygen supply conditions and specific biofilm interfacial area on the phenol removal rate in a three‐phase fluidized bed bioreactor were evaluated. The experimental data were well‐explained by the semi‐theoretical equation based on the assumption that the reaction rate follows first‐order reaction kinetics with respect to oxygen and zero‐order one with respect to phenol. Two cases, biological reaction as rate‐controlling step and oxygen absorption as rate‐controlling step, were both explicable by this semi‐theoretical equation. The maximum volumetric phenol removal rate was 27.4 kg·m^?3·d^?1.     

High-performance reflective STN-LCD with a blazed reflector

Abstract— A reflective super-twisted-nematic liquid-crystal display (STN-LCD) using a blazed reflector is proposed. Application of the blazed reflector improves luminance and contrast ratio in reflective LCDs by directing the reflected image toward the observer and also by misaligning it from the direction of the surface reflection. The reflector needs proper scattering to eliminate casting a background by a specular image. Therefore, we studied two methods: one which makes the surface of the reflector uneven and the other which applies light-scattering material between the display and the reflector. Key features include almost a doubling in brightness and contrast ratio using the blazed reflector with the light-scattering material. Moreover, good white representation is obtained to optimize the refractive index in the normal direction of the retardation film.     

Superconductivity in polycrystalline diamond thin films

Superconductivity was discovered in heavily boron-doped diamond thin films deposited by the microwave plasma assisted chemical vapor deposition (MPCVD) method. Advantages of the MPCVD deposited diamond are the controllability of boron concentration in a wide range, and a high boron concentration, especially in (111) oriented films, compared to that of the high-pressure high-temperature method. The superconducting transition temperatures are determined to be 8.7 K for T_c onset and 5.0 K for zero resistance by transport measurements. And the upper critical field is estimated to be around 7 T.     

On multi-objective optimization of geometry of staggered herringbone micromixer

A design methodology for micromixers is presented which systematically integrates computational fluid dynamics (CFD) with an optimization methodology based on the use of design of experiments (DOE), function approximation technique (FA) and multi-objective genetic algorithm (MOGA). The methodology allows the simultaneous investigation of the effect of geometric parameters on the mixing performance of micromixers whose design strategy is based fundamentally on the generation of chaotic advection. The methodology has been applied on a Staggered Herringbone Micromixer (SHM) at several Reynolds numbers. The geometric features of the SHM are optimized and their effects on mixing are evaluated. The degree of mixing and the pressure drop are the performance criteria to define the efficiency of the micromixer for different design requirements.     

Fabrication of highly porous keratin sponges by freeze-drying in the presence of calcium alginate beads

Novel fabrication method of highly porous and flexible keratin sponges was developed by combining a particulate-leaching method and a freeze-drying method. Reduced keratin aqueous solution was mixed with dried calcium alginate beads and was lyophilized to give keratin/calcium alginate complex, which was subsequently treated with EDTA solution to leach out calcium alginate beads. The resultant keratin sponge was flexible enough to handle even in dried state because of its quite high porosity (98.9 ± 0.1%), which was brought about by the large and small pores formed by the elimination of calcium alginate beads and water. The sponge supported the attachment and the proliferation of mouse fibroblast cells. Thus, the keratin sponge given by the present fabrication method afforded one alternative as a cell scaffold for tissue engineering.     

Sensorless salient‐pole PM synchronous motor drive in all speed ranges

This paper presents a position sensorless drive of salient‐pole PM synchronous motors in all speed ranges including zero speed. Two position and speed estimation algorithms using the current differences between the actual and the estimated currents are proposed. One is based on the back emf estimation in the medium‐ and high‐speed ranges. Another is based on the position dependency of the winding inductances in the low‐speed ranges including zero speed. The effectiveness of the proposed algorithm has been verified with a six‐pole, 1.5‐kW, 1500‐rpm test motor. Stable sensorless speed control from zero to 3000 rpm within ±100% load torque range was achieved. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 64–73, 2001     

Coupling simulation system of annual building energy and microclimate

We have developed a simulation system for a year-round assessment of environmental comfort, energy conservation, and CO₂ emissions in buildings and street blocks where active utilization of sunshine, vegetation and solar energy resources is fully considered. An analysis model has been constructed for handling interactions between highly complex street-block wide solar radiation patterns and building air-conditioning load. As a demonstration case of the present system, coupled solar radiation-thermal load analysis for an eleven-story office building has been performed. By comparing the result of a building located in a city block with a reference case of a self-standing building, the proper arrangement of buildings and spaces such as solar reflectance of building surface may be proposed.     

Stacking sequence optimization to maximize the buckling load of blade-stiffened panels with strength constraints using the iterative fractal branch and bound method

Laminated carbon fiber reinforced polymer (CFRP) composites have widespread applications in aerospace structures, and thus optimization of the stacking sequences in these composites is indispensable. Here, a fractal branch and bound method (FBB) is proposed for optimizing the stacking sequences. This method requires only low computational costs, and an optimal result can be obtained rapidly by means of the deterministic process. For practical stacking sequence optimizations, more than two laminates have to be optimized, because a practical aerospace structural component usually comprises a panel and stiffeners made from composite laminates. Since the stacking sequences of the skin panel and stiffeners affect the buckling load of the stiffened panel, the optimization of both laminates must be performed simultaneously. In the present study, a new method to implement a strength constraint for the FBB method is proposed for the simultaneous optimization of more than two laminates (such as a panel and stiffeners). Moreover, a quadratic polynomial objective function, which includes lamination parameter variables of the two laminates: the stiffeners and the panel, is adopted. The strength constraint is implemented by means of a response surface. The new method is applied to the buckling load maximization of a blade-stiffened composite panel, in which the strength constraint is demonstrated as a feasibility study. The method successfully obtained optimal stacking sequences with the strength constraint at low computational cost.     

Burning velocity measurement of fluorinated compounds by the spherical-vessel method

Burning velocity has been measured using the spherical-vessel (SV) method for four hydrofluorocarbons (HFCs), i.e., difluoromethane (HFC-32), 1,1,2-trifluoroethane (HFC-143), 1,1,1-trifluoroethane (HFC-143a), and 1,1-difluoroethane (HFC-152a). Experiments were conducted for initial pressures in the range 78-108 kPa and initial temperatures in the range 280-330 K, over wide ranges of HFC-air equivalence ratios. The burning velocities were determined from the rate of pressure increase by applying a spherical-flame propagation model. Flame propagation behavior was observed in a cylindrical vessel equipped with optical windows by employing schlieren photography. It was found that the values of burning velocity derived from the spherical-vessel method are in good agreement with the ones obtained with schlieren method. It is found that the SV method is adequate for determining the burning velocity for weakly flammable HFCs as well as for moderately flammable compounds. The burning velocity of each HFC was obtained as a function of temperature, pressure, and equivalence ratio. The maximum burning velocities of HFC-32, HFC-143, HFC-143a, and HFC-152a were determined to be 6.7, 13.1, 7.1, and 23.6 cm s⁻¹, respectively. The maximum burning velocity occurred for slightly fuel-rich concentrations. The magnitude of the burning velocity is strongly dependent on the ratio of H atoms to F atoms in the HFC molecules.