A probabilistic modeling of MOSAIC learning

Humans can generate accurate and appropriate motor commands in various, and even uncertain, environments. MOSAIC (MOdular Selection And Identification for Control) was originally proposed to describe this human ability, but this model is hard to analyze mathematically because of its emphasis on biological plausibility. In this article, we present an alternative and probabilistic model of MOSAIC (p-MOSAIC) as a mixture of normal distributions and an online EM-based learning method for its predictors and controllers. A theoretical consideration shows that the learning rule of p-MOSAIC corresponds to that of MOSAIC except for some points which are mostly related to the learning of controllers. The results of experiments using synthetic datasets demonstrate some practical advantages of p-MOSAIC. One is that the learning rule of p-MOSAIC stabilizes the estimation of “responsibility.” Another is that p-MOSAIC realizes more accurate control and robust parameter learning in comparison to the original MOSAIC, especially in noisy environments, due to the direct incorporation of the noises into the model. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Analyses of Instability in Mobile Cranes due to Ground Penetration by Outriggers

This study focuses on the phenomenon of ground instability causing mobile cranes to overturn. Four outriggers usually support a mobile crane in order to restrict pitching during hoisting operations. Nevertheless, the crane may become quite unstable if the outriggers should happen to sink into the bearing ground. In this paper, various types of analysis, including experiments, were performed in order to investigate the influence of ground penetration by outriggers on the stability of mobile cranes. Through study of the results of experimentation and simulation, it has been clarified that mobile cranes become highly unstable as a result of rapid penetration. It was found that an index of relative instability had a linear relationship to the common logarithm of an index for brittle failure as derived from the load–settlement curve for ground penetration. Finally, a method of evaluating the risk of mobile-crane overturning is proposed by using the maximum value of both the supporting surface’s failure risk and the kinetic risk due to ground penetration.     

Excellent compositional homogeneity in In0.3Ga0.7As crystals grown by the traveling liquiduszone (TLZ) method

The influence of convection in a melt on the compositional homogeneity of the TLZ-grown In_0.3Ga_0.7As crystals has been investigated by growing crystals with various dimensions on the ground. Excellent compositional homogeneity such as 0.3 plus or minus 0.01 in InAs mole fraction for a distance of 25 mm was obtained when the melt diameter was limited to 2 mm and convective flow in the melt was suppressed. On the other hand, when the crystal diameter was increased to 10 mm, both axial and radial compositional homogeneity was deteriorated due to convection in the melt. Comparing with the numerical simulation, convective flow velocity less than 1.4 mm/h may be sufficient for growing homogeneous crystals and it is not so difficult to suppress convective flow velocity below 1.4 mm/h for 10 mm diameter crystals in microgravity. Therefore, larger homogeneous In_0.3Ga_0.7As crystals are expected to be grown by the TLZ method on board the International Space Station.     

Design of a small‐size interlocking system with high availability

An interlocking system consists of an interlocking logical unit and a power controlling unit. After this logical unit calculates the relationship among the train position, the rail shifting position, and the signal, it decides the aspect of the signal. The power controlling unit supplies electrical power to the switch motor and the signal light according to the decision of the logical unit. This paper proposes a small‐sized interlocking system which uses a triplex redundant off‐the‐shelf controller with fail‐safe checker as an interlocking logical unit. A majority voting circuit ensures the safety of parallel output from the interlocking logical unit. This circuit satisfies the condition of total self‐checking (of D.A. Anderson) and also the condition of high availability. In other words, no single fault ever leads to a hazardous state and this circuit ensures safety after single fault occurrence. © 1999 Scripta Technica, Electr Eng Jpn, 128(2): 63–73, 1999     

Enzymatic Transesterification of 3,7-Dimethyl-4,7- octadien-1-ol Using Lipases

Enzymatic transesterification of (±)-3,7-dimethyl-4,7-octadien-1-ol ( 1 ) using various lipases and vinyl esters resulted in the formation of (S)-(+)-1-acyloxy-3,7-dimethyl-4,7-octadiene ((S)- 2 ) and (R)-(-)-3,7-dimethyl-4,7-octadien-1-ol ((R)- 1 ). Cyclization of (R)- 1 with iodine afforded (4R)-(-)-cis-4-methyl-2-(2-methyl-1-propenyl)tetrahydropyran ((-)-rose oxide). © 1997 SCI.     

Microporous polypropylene fibers containing fine particles of poly(glycidylmethacrylate-co-divinylbenzene)

Glycidylmethacrylate and divinylbenzene were copolymerized in a n-hexane solution of poly(propylene-co-1-butene). The resultant polymer composite contains fine particles of poly(glycidylmethacrylate-co-divinyl benzene). This composite was blended with polypropylene. Next, the resultant polypropylene composites were melt spun and stretched. Microporous polypropylene fibers were thus prepared and their properties were evaluated. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1549–1553, 1999     

Transient behavior of subcooled forced-convective boiling with twisted tape inserts

An internal twisted tape, when used to initiate subcooled swirling flow boiling, is a very effective method of cooling components which are subject to a high heat flux in a fusion reactor. In this study, the swirled channel was constructed using a copper cylinder (8 mm inside diam., 190 mm outside diam., and 100 mm heating length), which was equipped with a twisted aluminum tape (approx. 0.5 mm thick and 7.5 mm wide). The values of the tape-twist ratio y (the length required to complete a single 180-degree twist of the tape divided by the inside tube diameter) were approximately 1.8, 2.5, 3.2, 4.2, and infinity. Critical heat flux dependence on flow velocity and tape-twist was determined. Heating and cooling processes of large thermal capacity and inertia were used to obtain the wall heat flux via quasi-steady conditions, and several results for these limited cases are presented in the transition region near atmospheric pressure. © 1997 Scripta Technica, Inc. Heat Trans Jpn Res 25(3): 178–191, 1996