An adaptive algorithm based on the immune system and its application to adaptive noise neutralization

We propose an adaptive algorithm based on some features of the immune system (a selection-based mechanism compatible with Edelman’s selectionist principle, self/nonself reference, and negative/positive selection). The algorithm proceeds in three steps: diversity generation, establishment of self-tolerance, and memorizing nonself. This algorithm may typically be used to model the system of distributed agents where the system (the self) as well as the environment (the nonself) are unknown or cannot be modeled. An agent-based architecture based on the local memory hypothesis and a network-based architecture based on the network hypothesis are discussed. The agent-based architecture is elaborated with applications to an adaptive system where knowledge about the environment is not available. An adaptive noise neutralizer is formalized and simulated for a simple plant. Some part of this work has been presented at ICEC 1996, IROS 1996, and AROB 1999.     

Analysis of current distributions in a multi-laminated HTS tape conductor for solenoid coils

A multi-laminated HTS tape conductor has been recently developed for large coils. If the HTS tapes are simply laminated to form the conductor, the current distribution in the laminated tape conductor of the coil is imbalanced because of the differences among inductances of tapes. Transposition of the tapes in the conductor is effective for homogeneous current distribution, but the tape may be damaged due to the lateral bending. The solenoid coil has enough space to transpose the tapes at both ends. However, a proposed theory so far requires a restriction in the number of coil layers for homogeneous current distribution in the laminated tape conductor. It is very important to analyze current distributions in the multi-laminated tape conductor for the solenoid coil with arbitrary layers. In this paper, we apply the Maxwell integral equation to the region contoured by adjacent laminated tapes to analyze the current distributions of the tapes in an infinite solenoid coil, and demonstrate that the flux across the region is conserved as long as the tapes are not saturated, and finally induce the fundamental equations as functions of coil construction parameters, such as layer radii, laminated tape spaces, and winding pitches. We use the fundamental equations for 2-layer and 4-layer coils to verify the homogeneous current distribution of the laminated tape conductor for an arbitrary layer number. Since the flux between the tapes in the inner layer of a 2-layer coil is contributed from the outer layers, the tape space in the outer layer must be larger than that in the inner layer because of the balance between the two fluxes. Moreover, we have developed an analysis method for a finite solenoid coil.     

A network visualization of stable matching in the stable marriage problem

The stable marriage problem (SMP) seeks matchings between n women and n men which would result in stability, and not lead to divorce or extramarital affairs. We have introduced a network consisting of nodes which represent matchings, and links between nodes which attain stability by exchanging a partner between two pairs. The network is depicted with nodes laid out to involve several coordinates which indicate either women’s satisfaction or men’s or both. With the network visualization, regularity and symmetry can be made conspicuous in specific instances of the SMP such as the Latin SMP.     

Emergence of observable rules in a spatial game system

This study focuses on player’s strategies observed from outside our original spatial game iterated by players, each of which is placed in a lattice site on a two-dimensional square lattice. A particularity of the game lies in the fact that a player’s strategy is not given, but is constructed dynamically in response to the spatial pattern of the player’s actions. This means that the strategy can evolve in time. However, the simulations revealed unexpected results. It was found that all the strategies observed from outside did not evolve, but were fixed in time. This article enumerates all the observed strategies in detail, and examines their characteristics.     

Spatial strategies in a generalized spatial prisoner’s dilemma

Many strategies, such as tit-for-tat, have been proposed in the iterated prisoner’s dilemma (IPD) in which the prisoner’s dilemma (PD) is carried out repeatedly with two players. A spatial version of the iterated prisoner’s dilemma (SPD) has been studied, where a player at each site plays the IPD game with all the players in the neighborhood. However, the strategies studied in the SPD consider the past actions of a single opponent only. We studied spatial strategies that depend on the configuration of actions taken by all neighbors (as opposed to conventional temporal strategies). Since generosity can be considered as a spatial strategy, we first investigate the generosity required when an action error is involved. We also propose several spatial strategies that outperform many others.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004     

Partially Reduced Cuprous Oxide Nanoparticles Formed in Porous Glass Reaction Fields

This paper describes the formation of cuprous oxide (Cu₂O) particles ∼10 nm in diameter and their reduction by hydrogen gas in porous glasses. Nanoparticles of Cu₂O coated with metallic copper are expected to show high third-order optical nonlinear susceptibilities (χ⁽³⁾). The porous glass is a medium in which nanoparticles can be partially reduced without forming agglomerations. Images obtained using transmission electron microscopy showed that particles with the desired core-shell structure were actually formed, even though some particles were not reduced uniformly from the surface. The χ⁽³⁾/α (α: absorbance) values in relevant conditions (10⁻¹³ esu·cm) were similar to that of copper because of the formation of a byproduct of copper nanoparticles on reduction.     

Inactivation of rifampin by Nocardia brasiliensis

Rifampin was glycosylated by a pathogenic species of Nocardia, i.e., Nocardia brasiliensis. The structures of two glycosylated compounds (RIP-1 and RIP-2) isolated from the culture broth of the bacterium were determined to be 3-formyl-23-(O-[beta-D-glucopyranosyl])rifamycin SV and 23-(O-[beta-D-glucopyranosyl])rifampin, respectively. Both compounds lacked antimicrobial activity against other gram-positive bacteria as well as the Nocardia species.     

Direct Insight into Near-frictionless Behavior Displayed by Diamond-like Carbon Coatings in Lubricants

Surface physical properties and chemical states on a nanometer scale were investigated to provide a direct insight into the mechanism of near-frictionless performance displayed by diamond-like carbon (DLC) coatings in engine oil lubricants. A mechanism was revealed by combining nanoprobe methods with surface chemical analysis. The near-frictionless behavior observed in the lubricants was found to stem from strong repulsive force between hydrogen-terminated carbon chains, originating from the bonding of oil additive molecules on the DLC coating surface producing sliding contact between H-terminated alkyl chain layers.     

Effects of oily drug rheology on content uniformity in granules obtained by wet granulation with a high-shear mixer

The purpose of the present work was to elucidate the effects of viscosity on the content uniformity of an oily drug in granules obtained by wet granulation with a high-shear mixer. For this purpose, we used d-alpha-tocopheryl acetate diluted with a medium chain fatty acid triglyceride having viscosities in the range from 26.0 to 726.0 mPas. It was found that independent of viscosity, nuclei rich in the oily drug were formed in the process of mixing with powder and that those nuclei prevented uniform distribution of the drug throughout the granules. To achieve content uniformity, it is necessary for the nuclei formed before granulation to be fragmented and for the oily drug to be distributed uniformly throughout granules. Tensile strength of the nuclei was attributed to the viscosity of the oily drug, according to a model for tensile strength of a granule under dynamic conditions. When viscosity of the oily drug increased, tensile strength of the nuclei increased and the extent of the drug demixing in granules was large and constant independent of granulation time. On the other hand, when viscosity of the oily drug decreased, tensile strength of the nuclei decreased. The extent of the drug demixing was small with lower viscosity but increased with a prolonged granulation time. In the case of the oily drug, we found that a decrease in its viscosity led to the improvement of the content uniformity in granules. The viscosity of the oily drug significantly affects its content uniformity in granules by a high-shear mixer granulation.