Group replica caching scheme for optical grid networks

This paper proposes a cache replacement scheme named group replica caching for optical grid networks. In optical grid networks, data files for job execution are replicated at multiple servers in order to distribute loads. Clients download these files via lightpaths and store them as necessary. File downloading is blocked when the corresponding lightpath cannot be established. The blocking probability of file downloading depends on location of files. The case where a file is stored in a client is ideal because blocking of lightpath establishments does not occur. However, the storage size of the client is limited. In order to efficiently use storage resources of clients, our proposed scheme focuses on the fact that clients can download files stored in surrounding servers with low blocking probability. The proposed scheme regards a group of storages of a client and its surrounding servers as one storage. In particular, they preferentially store different files. By doing so, the probability that a file is stored at the client or its surrounding servers increases. Through simulation experiments, we show that the proposed scheme improves the blocking probability of file downloading efficiently.     

DIMERIZATION OF SOME CARBOXYLIC ACIDS IN ORGANIC PHASES

The partition coefficients and organic-phase dimerization constants of benzoic acid and three short-chain congeners of aliphatic carboxylic acids were investigated. In order to determine them, the “standard potential strength”was introduced for the first time. In low concentrations a carboxy-lie acid has been generally assumed to be almost exclusively monomeric in an organic phase, but the amount of its dimer form was not found to be negligible even in rather low concentrations. As its concentration increased, a proportion of the dimer form increased. In the cases of some nonpolar solvents, a nearly complete dimerization could occur at high concentrations. Although the partition coefficient and dimerization constant of an organic acid have been considered constant irrespective of acid concentrations in an organic phase, a closer observation suggested they should not be constant. This paper also reports the results of a comparative investigation on the degree of self-association (v) the modified potential strength and the half-dimerization concentration (Ch)among the carboxylic acids.     

Analytical study of optimal layout of permanent magnet in IPMSM for generating sinusoidal flux‐density distribution in air gap

This paper demonstrates an analytical optimization method for rotor designs of interior permanent magnet synchronous machines with multiple flux‐barriers. In particular, this study focuses on the optimal layout of permanent magnets for generating a sinusoidal flux density distribution in the air gap. In addition, practical design methods for realizing the optimal layout are proposed, and the designs are verified through finite‐element analyses. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(2): 39–46, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22344     

Basic study of loss reduction effect by Stator‐Tooth slits in turbine generators. comparison between calculated results of generators and basic experiments

In this study, we investigate the loss reduction effect by stator‐teeth slits in turbine generators on the basis of electromagnetic field analysis and basic experiments. First, the loss reduction effect in the generator is estimated by the 3D finite element method and the theoretical solution of eddy current loss. Next, an experiment using a simple model that simulates the stator‐core ends of the turbine generator is carried out. It is clarified that the loss reduction effect by the slits depends on the frequency, flux density, and permeability of the stator teeth because the loss reduction effect weakens with the skin effect. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 183(3): 17–25, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22345     

Structome of Saccharomyces cerevisiae determined by freeze-substitution and serial ultrathin-sectioning electron microscopy

The cell structure has been studied using light and electron microscopies for centuries, and it is assumed that the whole structure is clarified by now. Little quantitative and three-dimensional analysis of cell structure, however, has been undertaken. We have coined a new word, 'structome', by combining 'structure' and '-ome', and defined it as the 'quantitative and three-dimensional structural information of a whole cell at the electron microscopic level'. In the present study, we performed structome analysis of Saccharomyces cerevisiae, one of the most widely researched biological materials, by using freeze-substitution and serial ultrathin-sectioning electron microscopy. Our analysis revealed that there were one to three mitochondria, ~220 000 ribosomes in a cell, and 13-28 endoplasmic reticula/Golgi apparatus which do not form networks in the cytoplasm in the G1 phase. Nucleus occupied ~10.5% of the cell volume; cell wall occupied ~17%; vacuole occupied ~5.8%; cytoplasm occupied ~64%; and mitochondria occupied only ~1.7% in the G1 phase. Structome analysis of cells would form a base for the post-genome research.     

Effects of crystal phase transformation on tensile properties of polybutene‐1/cellulose composites

Morphologies and tensile properties of polybutene‐1 (PB), PB/fibrous cellulose (FC), and the PB/silanized FC with 3‐aminopropyltrimethoxysilane (APTMS) composites were studied. The scanning electron microscope micrographs exhibited the adherent PB parts on the FC and the silanized FC, suggesting that there was a certain affinity of PB to them. The spherulite observation suggested that there existed a secondary bonding between the PB and the FC or the silanized FC. These tensile properties were remarkably affected by the PB crystal phase transformation from the metastable tetragonal (II) to the stable hexagonal (I) phase. The transformation caused the ageing embrittlement even at r.t. In particular, the ageing embrittlement rate of the PB/silanized FC was much higher than other samples. Because the silanized FC became the excellent nucleating agent for the PB crystallization, the PB/silanized FC was found to easily form the thicker lamella having a higher probability of containing a crystal defect to serve as a starting point of the transformation. The higher transformation rate depended on the thicker lamella formation rate and its amount. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Wheel/rail contact geometry on tight radius curved track: simulation and experimental validation

In this investigation, a numerical procedure for wheel/rail one and two-point contact geometry analysis is developed for predicting the location of contact points in curved negotiations on a tight radius curved track. The proposed method accounts for the change in the longitudinal location of contact point along the curved track as well as the circumferential contact point on the wheel flange. For the purpose of validation, simulation results for one and two-point contact scenarios are compared with those obtained using the experiment. The experiment is performed on a test track of R48 curve using an actual truck, and the location of contact points for given lateral and yaw displacements are measured on the tight radius curved track. It is demonstrated that good agreements are obtained between the simulation and experimental results in tread and flange contacts.     

Preparation of ZrO<Subscript>2</Subscript> dielectric layers by subsequent oxidation after Zr film deposition with negative substrate bias voltage

ZrO₂ dielectric layers were prepared by a two-step process, a deposition of pure Zr film with and without a negative substrate bias voltage and a subsequent oxidation of the Zr films. We focused on the effect of the negative substrate bias voltage on the Zr film deposition and the subsequent oxidation of the Zr films. As a result, the Zr film deposited at the substrate bias voltage of −50 V (Vs = −50 V) was found to have a high intensity peak of Zr (100) and a uniform and smooth surface. From the capacitance-voltage and current-voltage measurements of the ZrO₂ films, a high dielectric constant of 21 and the equivalent oxide thickness (EOT) of 2.6 nm were obtained on the oxidation layer of the Zr film deposited at Vs = −50 V. On the other hand, a low dielectric constant of 15 and the EOT of 3.6 nm was obtained on that of the Zr film deposited at Vs = 0 V. The leakage current density of the ZrO₂ film (Vs = −50 V) was 5.69×10⁻⁴ A/cm², and this value was much lower than the 1.21×10⁻⁴ A/cm² for the ZrO₂ film (Vs = 0 V). It was found that the two-step process by subsequent oxidation after film deposition using a negative substrate bias voltage is useful for obtaining high-quality dielectric layers.     

Development of an Autonomous Mobile Robot with Several Sensors using Neuro‐Fuzzy Control Based on Server/Client Model

The purpose of this paper is to detail the development of an autonomous mobile robot and a control support system. The robot has five infrared sensors and three ultrasonic sensors to enable it to follow a ‘ guide person’ with an infrared ray transmitter. The robot will follow the infrared rays emitted by a transmitter with the guide person, and move to the destination. The control system has been developed by the network technology based on server/client model. The advanced control strategy for the autonomous mobile robot is carried out with a high‐speed host server computer connected through the TCP/IP network. Therefore, it is enough for the CPU of the robot to be of low speed. In this paper, the autonomous mobile robot system and the control system using the server/client model are described. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.