Development of Reference Shunt for Short‐Time Alternating High Current Tests and Study of Measuring System

Short‐circuit tests for power circuit breakers and others require alternative short‐time current measurement, from a few kA to over several tens kA. However, the reference measurement system as a national standard or a specified secondary standard instrument to directly perform comparative test as a complete calibration test in high current class has not yet been established globally. The Japan Short‐Circuit Testing Committee (hereinafter referred to as “JSTC”) has therefore developed a shunt resistor that can be used as a standard instrument for high current measurement. Reference system using this shunt resistor is also considered by JSTC. The performance of the newly developed shunt resistor has been checked through several methods, such as resistance measurement, high power current test, high frequency current test, temperature rise test, and interference test. The results of the tests proved satisfactory performance. Resistance of the shunt resistor before and after the tests was invariant and stable. This makes the shunt resistor adequate for a reference in practical use. In addition, evaluation of uncertainty of the whole reference system including this shunt resistor satisfactorily fulfills the requirements of IEC 62475 edition 1.0, 2010.     

Basic Study on Islanding Detection Method for PV Systems by Harmonic Impedance Detection in Case of Including Induction Motor in Load System

It is important that photovoltaic (PV) systems detect islanding caused by power system faults to ensure electrical safety. Thus we propose a novel islanding detection method which detects the harmonic impedance by injecting harmonic currents synchronized with the exciting current harmonics of the pole transformer. For the case in which an induction motor load is included in the load system, basic experiments on islanding detection and simulation analysis are conducted to verify the effectiveness of the proposed method.     

Lightning Observation in 3D Using a Multiple LF Sensor Network and Comparison with Radar Reflectivity

A three‐dimensional (3D) lightning mapper consisting of multiple low‐frequency (LF) sensors has been developed to monitor thunderstorms and to estimate their charge structure. We have been conducting an observation campaign using the 3D lightning mapper in Kansai, Japan, since October 2012. In this study, we determine 3D source locations of intracloud and cloud‐to‐ground flashes and compare them with the radar reflectivity estimated by phased‐array radar (PAR) with high temporal and spatial resolution. Most LF sources are located in high radar reflectivity regions, confirming that the 3D LF lightning mapper monitors thunderstorms. A lightning flash with heavy branches is clearly imaged. Based on the bidirectional leader theory that negative and positive ends of a lightning leader develop simultaneously, we estimate the positive and negative charge regions in a thundercloud from the LF source locations. The radar reflectivity estimated by PAR supports the charge structure estimated by LF source locations.     

Distortion correction of NOAA image by statistical method

Remote sensing technique by satellite has been well-developed in recent years. In this paper two kinds of statistical correction methods are proposed to clarify observation data by NOAA with atmospheric scattering. The first method is the deletion of the path radiance effect by the least squares method. The second uses a smoothing filter. These methods are applied to the original remote sensing data collected on 26 July 1987.     

Parallel Multipopulation Differential Evolutionary Particle Swarm Optimization for Voltage and Reactive Power Control

This paper presents parallel multipopulation differential evolutionary particle swarm optimization (DEEPSO) for voltage and reactive power control (VQC). The problem can be formulated as a mixed integer nonlinear optimization problem and various evolutionary computation techniques have been applied to the problem including PSO, differential evolution (DE), and DEEPSO. Since VQC is one of the online controls, speed‐up of computation is required. Moreover, there is still room for improvement in solution quality. This paper applies parallel multipopulation DEEPSO in order to speed up the calculation and improve solution quality. The proposed method is applied to IEEE 30, 57, and 118 bus systems. The results indicate that the proposed method can realize fast computation and minimize more active power losses than the conventional evolutionary computation techniques.     

BIDIRECTIONAL TRANSMISSION OF ADDRESSED AUDIO SIGNAL THROUGH GI MULTIMODE OPTICAL FIBRES

This paper describes two types of bidirectional addressed audio signal transmission systems where the square-wave frequency modulation (SWFM) and intensity modulation (IM) are used to obtain the optical SWFM signals generated from LEDs at 850 nm. The first one is an addressed audio signal transmission network of tree structure. The sender and auxiliary receiver in the centre are connected to four terminals, each consisting of a receiver and an auxiliary sender, through pairs of optical fibres and an optical splitter used as an optical signal distributor. The second one is a new type of full-duplex one-to-one communication system. The sender and auxiliary receiver in one terminal are connected to the receiver and auxiliary sender in the other terminal through an optical fibre and a pair of directional couplers. Although LEDs in the second system deliver optical SWFM signals at the same wavelength of 850 nm at the same time, the communications are satisfactory because there is no interference from one LED to the other. In both the first and second experimental systems, the audio signal, address, and SWFM carrier occupy 10 Hz to 20 kHz, 65 kHz to 710 kHz, and 6 MHz, respectively. The SNR and distortion were 62 dB and 0.4 per cent, respectively.     

A New Aroma-Bearing Substance from Shiitake, an Edible Mushroom

SUMMARY— Investigations on the physico-chemical properties and a sensory evaluation as a component of Shiitake flavor were carried out with lenthionine, a substance which was isolated from dried Shiitake mushroom. Lenthionine is practically insoluble in water but soluble in non-polar solvents. Its stability in an aqueous solution changes greatly with the pH of the solution.
Lenthionine was identified as a significant component in the aroma of Shiitake mushroom and its detectable threshold level is at a concentration between 0.27 and 0.53 porn in water. This new aroma-bearing substance will be used as a flavor additive in various foods.     

An experimental study on self-output-control characteristics of micro downwind rotor with coning soft blades

In this short paper,we have treated the aerodynamic performance of micro downwind rotor with coning soft blades experimentally.The test wind rotor has the tip diameter of 1.5 m and three two-dimensional NACA0018 blades of 0.15 m chord whose material is light,soft and pliable foam plastic for perfect safety.From the wind tunnel test,it is realized that the performance is manageable by the coning angle of the rotor blade.In the present case,an improvement of the performance in lower wind speeds is achieved by...     

Effects of Microwave Heating on the Molecular Species of Soybean Triacylglycerols

Microwave heating of whole soybeans resulted in an apparent increase of the total lipids. Molecular species of triacylglycerols were isolated from total lipids by a combination of silicic acid column chromatography and AgNO₃-thin layer chromatography (TLC). Fifteen molecular species of triacylglycerols were still found in whole soybeans following heat treatment. Microwave heating for about 5 min did not change all molecular species of soybean triacylglycerols nor cause a loss of unsaturated heat fatty acids. However, heat treatment for 8 min significant decrease not only in molecular species containing more than four double bonds, but also in the amount of diene and triene present in a triacylglycerol.     

Effects of Microwave Treatment on the Trypsin Inhibitor and Molecular Species of Triglycerides in Soybeans

Whole soybeans at different moistures (8.6, 24.3, and 49.7%) were heated by exposure to microwaves at frequency of 2,450 MHz. The trypsin inhibitor in soybeans at 24.3% moisture, soaked for 1 hr, was completely inactivated after treatment for 4 min, which was shorter than the heating period (6 min) needed for unsoaked soybeans. However, the trypsin inhibitor in soybeans at 49.7% moisture, soaked for 5 hr, was not completely inactivated even after heating for 12 min. The loss of molecular species of soybean triglycerides containing more than four double bonds in a triglyceride was less for soaked soybeans than for soybeans before soaking (8.6% moisture).