Economical preventive control of power flow after disturbances in the decentralized power system

This paper discusses the preventive controls of the generator outputs to improve security in the decentralized power system. Preventive controls of the power system can improve security level. However, the preventive control requires too much computation time because of too many considerable faults in the power system. Multiarea decentralization can be considered to reduce computation time of the power flow calculation. It is assumed that the effects of disturbances in the external systems are relatively smaller than the effects of disturbances in the study area. Linearized sensitivity analysis is used to evaluate the effects of the external systems to reduce computation time. Linear programming is used to determine the control signals of generators considering the incremental cost of generators. The New England 38 buses system is used as an example system to check the validity of the algorithm in this paper. The calculations of the example system show satisfactory results.     

Ceramic capillary splices for optical fibres

A simple technique for splicing optical fibres is reported. The technique utilises a self-aligning ceramic capillary with inner dimensions slightly larger than the optical fibre. An average loss of below 0.1 dB is obtained for splices in graded-index and single-mode fibres with a 50 and 10 ?m core diameter, respectively.     

Preparation of mercaptoethylated graft fibers for adsorption of heavy metal ions

Various kinds of mercaptoethylated graft fibers were prepared and the abilities to adsorb the heavy metal ions were studied. 2-Hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and vinyl acetate were graft-copolymerized by irradiation onto five kinds of synthetic fibers and two kinds of foam polymers. Preirradiation at low temperature was far more effective for grafting than simultaneous irradiation. The mercaptoethylation was carried out in the solution or in the vapor of ethylene sulfide onto the graft fibers treated with alkali. The mercaptoethylated graft fibers showed particular affinity for Hg and Ag ions. A few of the adsorption phenomena were pursued by flow experiment of the ionic solution through a column. The preliminary reduction of the mercaptoethylated graft fibers enhanced the capacity of adsorbing to three times that of the unreduced fibers. Effects of flow rate, pH, temperature, and concentration of Hg ion on the integrated adsorbed amount were also investigated.     

Synthesis of Mullite Whiskers and Their Application in Composites

Mullite whiskers were synthesized by a vapor-solid reaction. Mullite composition xerogels were fired at 900° to 1600°C with AlF₃ in an airtight container. An average whisker increased in length from 7 μm at 1100°C to 10 μm at 1600°C, whereas an average whisker decreased in aspect ratio from 25 to 10 with increased firing temperature. The whiskers elongated to the c -axis and the side planes were the {110}. A clear lattice image corresponding to (110) lattice spacing up to the edges of the whiskers was observed with high-resolution electron microscopy, and no droplet was observed on the tips of the whiskers. The chemical composition of the whiskers synthesized below 1100°C showed an apparent Al₂O₃-rich composition of about 72 mol%. Composites reinforced by 15 vol% of mullite whiskers in the matrix of 75 vol% mullite/25 vol% Y-TZP enhanced the fracture toughness compared with those materials without mullite whiskers.     

Application of FeOC1 derivatives as cathode materials for secondary lithium battery II. Comparison of the discharge and charge characteristics of γ-FeOOH prepared from the intercalation compound of FeOC1 and 4-aminopyridine with those of FeOOH intercalated with aniline (a-FeOOH(AN))

The discharge and charge characteristics of γ-FeOOH products prepared from the intercalation compound of FeOC1 and 4-aminopyridine were investigated in lithium cells and compared with those of FeOOH prepared from the intercalation compound of FeOC1 and aniline (a-FeOOH(AN)). The polarization of γ-FeOOH cathode during the discharge and charge were larger than those of an a-FeOOH(AN) cathode. The electrochemical characteristics of the FeOOH products depend on the amorphous nature of the cathode material.     

Hydrogen production from water by reduced tin oxide

The production of hydrogen from water by reduced tin oxide has been examined under various experimental conditions. It has been concluded that the reactive species decomposing water is metallic tin. The coexistence of SnO₂ with metallic tin enhances the rate of hydrogen production remarkably. The effect of SnO₂ has been ascribed to the enlargement of surface area of tin metal by its dispersion on the surface of SnO₂. Solid additives such as Pd, Pt, WO₃, CuO and CaO showed a large promoting effect for hydrogen production. The effect of the additives may be explained by increase in the surface area of tin metal or by the spill-over of the activated water by additives onto the surface of SnO₂ or tin metal.     

Contact force detection on a minute aperture mounted optical contact slider using an acoustic emission sensor

Advances in the digital network society require both higher density and higher transfer rates in all sorts of storage systems. Especially in optical recording, the trend toward higher density and larger capacity requires novel surface-recording technologies that can drastically diminish head-to-medium spacing, resulting in an improvement in spatial resolution and, finally, a higher recording density. To this end, we have already proposed a novel contact optical head slider that is able to almost cancel the suspension load by generating hydrodynamic pressure, thus realizing a lower net contact force. Evaluating the dynamic contact force is requisite in realizing its stable sliding operation and higher signal readout performance. In this study, a continuous acoustic emission (AE) signal was utilized to detect the dynamic contact force. AE signal modulation was compared with the applied out-of-plane acceleration on a medium generated by a spindle combined piezo-electric actuator. It was clarified that the detected AE modulation amplitude was approximately proportional to the applied acceleration, and that utilizing AE modulation will be a useful method for evaluating dynamic contact force.     

Thermal properties of ionomer

A series of resol-type phenol-formaldehyde resins with varying phenol/formaldehyde (P/F) molar ratio were investigated by infrared spectroscopy. The infrared spectroscopic data suggest that absorbance ratio of D₂₉₂₀, D₁₆₁₀, D₁₁₅₀, D₁₀₁₀, and D₇₆₀ based on 1 590 cm^?1 band can be used for the determination of phenol/formaldehyde molar ratio of the resins.     

Graphical editing and analysis system for network system (Geans)

Network analysis is powerful in building formal network models of various computational systems or social systems and obtaining their functions and performance exactly because of simplicity of binary relations in networks. Traditionally, it takes lots of effort in network analysis because network analysis was performed by the use of lots of numerical data in batch processing form. Effective network analysis activity, satisfying the system requirements based on consideration for such traditional manner with high cost, requires semiautomatic or computer aided man-machine facilities with interactive editing, analysis, and result viewing functions. We have developed Graphical Editing and Analysis system for Network System (Geans) on DEC PDP-11/34 minicomputer with a graphic display which enables us to edit or modify various network representations and analyze their qualitative and quantitative property, smoothly and interactively with the use of graphics and data abstraction. Geans is composed of a network editing system with effective use of a graphic display, a network data management system with systematic use of network data abstraction, a network analysis system with construction of shared library routines and specific object problem oriented routines, and a node/arc shape definition system. Geans has been applied to various network models such as a transportation analysis problem, PERT/CPM planning, Petri Net analysis and a guidance system for an urban railway network, and moreover it is being applied to other analysis areas as evolving itself.     

Improvement in the remaining activity of freeze-dried xanthine oxidase with the addition of a disaccharide–polymer mixture

In order to improve the remaining activity of a practically important freeze-dried enzyme, xanthine oxidase (XOD), the effects of disaccharide (sucrose and trehalose), polymer (bovine serum albumin: BSA and dextran) and a mixture of them on the loss of XOD activity during freeze-drying and subsequent storage were investigated. All samples were amorphous solids and their glass transition temperatures (T_g) were evaluated by using differential scanning calorimetry. Although dextran showed no stabilizing effect on the freeze-dried XOD, the others protected XOD from the activity loss during freeze-drying to a certain extent. It was found that the mixture of disaccharide (sucrose or trehalose) and BSA improved the XOD activity synergistically. The XOD activity of the samples decreased gradually during storage at a temperature range of between 25 and 60 °C. Samples stored at temperatures below the T_g showed a lower loss of XOD activity than those stored at just the T_g.