Control of three‐synchronous‐generator infinite‐bus system by OGY method

Stability of a power system has been investigated in terms of chaos and bifurcation. In this paper, the OGY (Ott–Grebogi–Yorke) method for controlling chaos of three machines operating onto an infinite‐bus system is investigated by computer simulations. The swing equation with the controlling input u is used. The OGY method is extended to the form in the six‐dimensional space. The eight equilibrium points are obtained. The swing equation is normalized and transformed into a discrete‐time state equation from which the control input is calculated. The time series of the phase angles of generators without the control input show the chaotic irregular motion and the step‐out. The time series of the phase angle of generators with the control inputs by the OGY method show the stable motion. The phase angles are successfully controlled onto the unstable equilibrium points with the three unstable manifolds and the three stable manifolds. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 151(2): 32–39, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20008     

Measurement and correlation of liquid-liquid equilibria for polystyrene-cyclopentane and polystyrene-cyclopentane-cyclohexane systems

Liquid-liquid equilibrium data for the polystyrene-cyclopentane binary system and the polystyrene-cyclopentane-cyclohexane ternary system were measured by observing the cloud points at the temperature range in which the systems showed their lower critical solution temperature. The experimental liquid-liquid equilibria were correlated successfully by the UNIFAC-FV model with adjustable parameters.     

Rectifying inspection for acceptable quality loss limit based on variable repetitive group sampling plan

It is usually assumed that a quality characteristic in an item obeys a normal distribution in the case that the quality of items is evaluated based on the variable property. Then, the concept of Taguchi’s quality loss has been accepted as the evaluation measure of quality instead of the traditional attribute property such as the proportion of nonconforming items. From this viewpoint, some variable sampling plans indexed by the quality loss have been investigated before now. As a study earliest among them, the variable single sampling plan based on operating characteristics (OC) indexed by the quality loss was considered. On the other hand, the attribute repetitive group sampling plan on OC was proposed for reducing the sampling number in the inspection. Recently, the variable repetitive group sampling (VRGS) plan on OC indexed by the quality loss has been considered. By the way, the rectifying inspection is known as one of the schemes of acceptance sampling inspection. Then, Dodge-Romig single sampling plans are known as the traditional rectifying inspection based on attribute sampling plans. Dodge-Romig rectifying attribute sampling plans provide the lot tolerance percent defective (LTPD) scheme on each lot and the average outgoing quality limit (AOQL) scheme for many lots. Furthermore, the rectifying variable single sampling (RVSS) plan indexed by the quality loss was investigated. In conformity with the traditional rectifying attribute sampling plans for the LTPD and AOQL schemes, the acceptance quality loss limit (AQLL) and specified permissible average outgoing surplus quality loss limit (PAOSQLL) schemes are respectively proposed in the RVSS plans indexed by the quality loss. In this article, we suppose that the quality characteristic in an item obeys a normal distribution. Under this condition, the rectifying variable repetitive group sampling (RVRGS) plan for AQLL is considered for the purpose of reducing the average total inspection (ATI). Specifically, the design procedure for finding out the required sample size and inspection criteria for satisfying the constraint of the quality assurance is derived. Lastly, it is shown that ATI of the RVRGS plan is reduced in comparison with that of the RVSS plan under the same condition.     

Tunability of form birefringence induced by femtosecond laser irradiation in anion‐doped silica glass

Form birefringence originating from self‐assembly of the bulk nanograting structures in silica glass with various anion dopants (OH, Cl and F) was induced by the femtosecond laser pulses. Despite the almost similar nanostructure, the photo‐induced birefringence can be changed by the anion dopants in glass. Larger birefringence can be induced in silica glass doped with higher Cl ion concentration. Even if F‐doped silica glass indicates lower thermal stability, its lifetime could be evaluated to be at least several billion years.     

Optical doping: active control of metal-insulator transition in nanowire

The reversible control of metal-insulator transition (MIT) in In/Si(111) nanowires is demonstrated by tuning the band filling of the one-dimensional surface state by optical doping. The control of MIT is carried out by regulating the Fermi level in the surface state around the half-filled position, depending on the carrier density introduced at the interface. We successfully achieved the reversible and active control of MIT via the charge doping by regulating the intensity of photoexcitation. This method is widely applicable to other low-dimensional systems and makes MIT more controllable and suitable for use in nanowires as an active element in future architectures of nanosized functional devices as well as nanoscale interdevice wiring.     

Evaluation of the precautionary action zone using a probabilistic consequence analysis

To develop an effective emergency plan for a nuclear accident, the size of the precautionary action zone (PAZ) was evaluated using a Level 3 probabilistic safety analysis (PSA) code, the OSCAAR. For accident scenarios identified through a Level 2 PSA analysis for representative boiling water reactor (BWR) and pressurized water reactor (PWR) plants, the absorbed doses to red marrow were calculated as a function of the distance from the accidental site for possible weather sequences in a year, and then the evaluation was made for the distance which satisfies the dose criterion of 1 Gy for acute exposure, as established in the Basic Safety Standards (BSS) of the International Atomic Energy Agency (IAEA). Consequently, the present study indicated that the size of the PAZ should be approximately a 3-km radius under average weather conditions.     

Vacuum and Pressured Combinatorial Processings for Exploration of Environmental Catalysts

Two types of combinatorial chemical reactors have been developed for high-throughput experimentation of catalysts that attract much interest from global environmental viewpoints. The high vacuum combinatorial laser MBE system was applied to the preparation of thin film library of TiO₂ with its film thickness gradually increased, which resulted in the discovery of new phenomenon indicating a quantum size effect in TiO₂ photo-catalysis. The combinatorial autoclave reactor was made to explore new catalysts and optimum reaction conditions efficiently for alternating CO₂ copolymerization with epoxide (oxirane) to form bio-degradable polycarbonates. Some preliminary results are reported on the CO₂ copolymerization with propylene oxide, as a means of CO₂ fixation into chemically useful material.