Parallelization of genetic algorithm with sexual selection

We propose a parallel genetic algorithm with sexual selection. In genetic algorithms with sexual selection with one population, females keep their traits around local optima by using a lower mutation rate than that of the males, while the males change their traits actively. When a runaway process takes place, the transitions of the males' traits are biased toward a certain direction which depends on the bias of the females' preferences. If the population size is large, the search converges quickly. However, the large population size causes a decrease in search performance. In the proposed method with parallelization, the population size of each subpopulation is maintained adequately, and each subpopulation seeks its own direction of evolution independently. As a result, the proposed method makes a search converge quickly because the runaway process which leads to intermittent evolution tends to take place more quickly than one population model. We applied the proposed method to some test problems. In these problems, while the performance of conventional genetic algorithms was decreased by parallelization, the proposed method exhibited better performance with parallelization. Moreover, the performance of the proposed method is better than that of conventional methods. This capability of parallelization is a remarkable characteristic of sexual selection. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(1): 42–49, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20029     

Manufacturing and material properties of ultralarge size forgings for advanced BWRPV

Ultralarge size forgings for the advanced boiling water reactor (ABWR) pressure vessel as represented by the bottom petal made from a 600 ton ingot have been developed. The bottom petal is a larger wall thickness ring with 10 integrated nozzles inside and outside the ring. The outer diameter is 7.8 m, the height is 1.8 m and the wall thickness if 1.1 m in the as-forged condition. A very high purity level of P 0.003% and S 0.003% can be obtained by the application of double-refining processes to all the molten steel. The forging shows a homogeneous chemical distribution, sound internal qualities and adequate impact properties.This paper summarizes the manufacturing technique and material properties of large size forgings such as the bottom petal, the shell with integrated skirt and the bottom dome.     

Light emission in PE with a needle-like microvoid at themetal-polymer interface under impulse voltages

Light emission from polyethylene with a needle-like microvoid has been investigated under the application of a negative impulse voltage in order to examine the temporal behavior of discharge in the microvoid at the metal-polymer interface. The light emission was observed distinctly during the voltage rise and fall phases with a period of no light emission between the two light emitting phases. The emitted light consisted of sequential light pulses which appeared regularly, according to the temporal variation rate of the voltage. The sequential light pulses corresponded to the sequential discharge in the microvoid which occurred to keep the voltage across the microvoid below the discharge inception voltage. The characteristics of light emission revealed the occurrence of intermittent discharges in the microvoid during the voltage variation phase of the impulse voltage, caused by charge deposition on the polymer surface of the microvoid     

Impurity Scattering Effect on Superfluid Phases of 3He in 97.5% Porous Silica Aerogel

No Heading NMR studies of superfluid ³He in 97.5% aerogel have been performed in a magnetic field of 28.4 mT. A small-angle neutron scattering experiment on the structure of the aerogel shows that the average separation distance of silica strands is 54 nm. The aerogel strands were covered with a few layers of solid ³He whose magnetization shows Curie-Weiss behaviour. On cooling process A-like phase appeared at suppressed superfluid transition temperature T_C^aero and B-like phase appeared at lower temperatures although only the B-like phase was observed up to T_C^aero on warming process above 2.1 MPa. The superfluid transitions in aerogel always occur below the AB phase transition temperature of bulk liquid at all pressures. An isotropic inhomogeneous scattering model(IISM) proposed by Thuneberg et al. explained well the observed suppressed T_C^aero in 97.5% with the radius 59 nm of voids in this model. This radius is similar with the average strand separation distance of 54 nm measured in the structural analysis. This similarity of two lengths shows the connection of the suppression of T_C^aero with the actual average separation distance of the silica strands.PACS numbers: 67.57.Pq, 67.80.Jd     

Prevention of vestibular deafferentation-induced spontaneous nystagmus with pretreatment of Ca2+ channel/N-methyl-D-aspartic acid receptor antagonists in guinea pigs

Involvement of Ca2+ channel and N-methyl-D-aspartic acid (NMDA) receptors with induction of the spontaneous nystagmus (SN) after unilateral labyrinthectomy (UL) was evaluated by examining the effect of verapamil and MK-801 in guinea pigs. An injection of verapamil or MK-801 before the intratympanic application of arsanilate significantly (p < 0.05) suppressed the frequency of the SN towards the arsanilate-applied side. The frequency of the SN towards the intact side in these drug-treated animals was much lower than in the control animals until 36 h after the application of arsanilate. In addition, 60 days subsequent to induction of the UL, application of the drug before we injected the arsanilate into the opposite middle ear suppressed the SN towards the second arsanilate-injected side, but not towards the first injection side. We suggest that Ca2+ channel and NMDA receptor may be involved in the induction of the SN, and that the pretreatment of their antagonists could be applied in preventing the vestibular deafferentation-induced SN.     

Formation of an Orientation Preference Map – Gradual Inhibition Method

Formation of an orientation preference map due to external visual stimuli in the primary visual area of the cerebral cortex is investigated in a two-layered neural network model, where a cluster learning rule is used together with ordinary Hebbian learning rule. We succeed in solving directly a set of simultaneous equations by numerical iterations using a gradual inhibition method. Previously, an alternative solution was found by applying a Self-Consistent Monte Carlo (SCMC) method. The gradual inhibition method in an iterative procedure can give a more precise solution efficiently with fewer computational tasks than the SCMC method.     

Preparation of ultrafine metal particles supported on alumina by pyrolysis of polymer complex/alumina composites

Ultrafine metal particles supported on alumina were prepared by pyrolysis of poly(vinylferrocene) (Poly(VFc))/alumina or sodium polyacrylate-Pd(II) (Poly(AANa)-Pd(II))/alumina precursors at 800 ～ 1200°C. α-Fe particles produced on k-Al₂O₃ was obtained by pyrolysis of the mixture of Poly(VFc)/alumina(5/5) at 1000°C. Crystalline Pd supported on alumina was also obtained from Poly(AANa)-Pd(II)/alumina precursor. The size of metal particles formed increased with increasing mixing ratio of polymer complex with alumina. © 1994 John Wiley & Sons, Inc.     

A method for selecting similar learning data in the prediction of time series using neural networks

This paper explores a method of improving the predictive performance by the multi-layer feedforward neural network in time series predicting. For the similar data selective learning method, we propose a method of weighting the distance by a power function of correlation coefficients for the time series (CSDS method). The results of numerical experiments show that with the case of a time series whose nature is rather choppy or chaotic, using the CSDS method appropriately is considerably effective to improve the predictive performance and its performance is considerably better than that by the previously proposed other methods.