Effect of substrate temperature on the structure and magnetic properties of CoPt/AlN multilayer films

The effect of substrate temperature on the structure and magnetic properties of CoPt/AlN multilayer films has been investigated.The crystallinity of CoPt has been improved with increasing substrate temperature from room temperature to 400 ℃.After post-annealing process,L1_0 CoPt structure transformation has also been promoted.However,since the easy magnetic axis of L1_0 CoPt is in[001]orientation,the promotion of L1_0 CoPt transformation causes the change of easy magnetic axis in(111) textured CoPt layers,which impairs the perpendicular magnetic anisotropy.The optimum substrate temperature should be room temperature to obtain the strongest perpendicular magnetic anisotropy according to the results of the present work.     

Operation Optimization of Factory Power Generation Plant Considering an Uncertainty

Factory power generation plants supply electric power and heat to manufacturing lines. Because demand changes are uncertain, the power plant must adjust its output to match the demand and to avoid violation of constraints such as inverse load flow. Conventionally, these violations have been avoided by purchasing surplus electric power. However, surplus power raises the energy cost. There exists an optimization method that considers uncertainty in demands for cogeneration systems, and uses a triangle function to approximate the probability distribution. However, this method does not consider the tail of the probability distribution. In this paper we propose an operation optimization method considering an uncertainty in the demands for factory power plants. The proposed method aims to avoid violation of constraints and to reduce energy cost. Through simulation experiments, we confirm the validity of the proposed method.     

An effect of scraper shapes on detachment of solid adhered to cooling surface for formation of clathrate hydrate slurry

In air‐conditioning systems, it is desirable that the liquid– solid phase change temperature of a cool energy storage material is approximately 10^°C from the perspective of improving the coefficient of performance (COP). Moreover, a thermal storage material that forms slurry can realize large heat capacity of working fluids. Since the solid that adheres to the heat transfer surface forms a thermal resistance layer and remarkably reduces the rate of cold storage, it is important to avoid the adhesion of a thick solid layer on the surface so as to realize efficient energy storage. Considering a harvest type cooling unit, the force required for removing the solid phase from the heat transfer surface was studied. Tetra‐n‐butylammonium bromide (TBAB) clathrate hydrate was used as a cold storage material. The effect of the scraper shapes on the scraping force for detachment of the adhered solid of TBAB hydrate to the heat transfer surface was examined experimentally. The TBAB hydrate solids were categorized broadly into two kinds of solids. The scraping force of the TBAB hydrate solid on the heat transfer surface was different for the two kinds of the TBAB hydrate solids. And the scraping force of the TBAB hydrate solid formed after scraping was improved by the modifying the scraper shape. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(8): 489– 500, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20179     

Practical silicon-based composite anodes for lithium-ion batteries: Fundamental and technological features

Despite recent worldwide research efforts, composite silicon-based anodes remain at the centre of debate in the field of lithium-ion batteries. Here, we demonstrated that successful development of composite silicon-based anodes requires the simultaneous consideration of two equally important features: fundamental and technological. The fundamental feature dictates that the in situ formed amorphous phase should remain in its amorphous state in order to achieve a long-lasting reversible electrode, while the technological feature implies that the complex active material–binder interactions have to be numerically evaluated in order to tailor the electrode properties in an appropriate way. Only the harmonic consideration of both aspects allows creation of a long-lasting reversible silicon electrode. Examples demonstrating these features are considered and lithium-ion batteries employing hybrid silicon-based electrodes are proposed.     

Fatigue crack growth mechanism in cast hybrid metal matrix composite reinforced with SiC particles and Al2O3 whiskers

The fatigue crack growth (FCG) mechanism of a cast hybrid metal matrix composite (MMC) reinforced with SiC particles and Al₂O₃ whiskers was investigated. For comparison, the FCG mechanisms of a cast MMC with Al₂O₃ whiskers and a cast Al alloy were also investigated. The results show that the FCG mechanism is observed in the near-threshold and stable-crack-growth regions. The hybrid MMC shows a higher threshold stress intensity factor range, ΔK_th, than the MMC with Al₂O₃ and Al alloy, indicating better resistance to crack growth in a lower stress intensity factor range, ΔK. In the near-threshold region with decreasing ΔK, the two composite materials exhibit similar FCG mechanism that is dominated by debonding of the reinforcement–matrix interface, and followed by void nucleation and coalescence in the Al matrix. At higher ΔK in the stable- or mid-crack-growth region, in addition to the debonding of the particle–matrix and whisker–matrix interface caused by cycle-by-cycle crack growth at the interface, the FCG is affected predominantly by striation formation in the Al matrix. Moreover, void nucleation and coalescence in the Al matrix and transgranular fracture of SiC particles and Al₂O₃ whiskers at high ΔK are also observed as the local unstable fracture mechanisms. However, the FCG of the monolithic Al alloy is dominated by void nucleation and coalescence at lower ΔK, whereas the FCG at higher ΔK is controlled mainly by striation formation in the Al grains, and followed by void nucleation and coalescence in the Si clusters.     

Strategy for preventing bacterial contamination by adding exogenous ethanol in solid-state semi-continuous bioethanol production

A strategy for preventing reduction of ethanol yield in fermentation caused by bacterial contamination was developed. In solid-state ethanol fermentation in which saccharification, fermentation and ethanol recovery are performed simultaneously, the addition of exogenous ethanol to the fermentation mixture at the start of fermentation at 50 g kg(-1) prevented contamination, and the ethanol yield reached 0.50 g g(-1).