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.     

Enlargement of Claw Pole Motor Using SMC Cores Divided in the Circumferential Direction

Clawtooth motors have the feature that they can be made thin in the axial direction. This makes them suitable for appliances, automobile accessories, and small‐sized industrial motors. On the other hand, there is a need for thinner HEV and elevator motors and large‐sized industrial motors. In this study, we examined ways of increasing the output of clawtooth motors. We arrived at the following conclusions. (1) The optimal stator structure was determined and the prospects of attaining the target specification of 123 N‐m were determined. (2) Three important manufacturing tasks, assurance of core assembly accuracy, thin coil manufacture, and rotator insertion, were identified. (3) Experimental results and the results of analysis were in agreement with respect to the EMF. (4) The experimental cogging torque results and finite element analysis (FEA) results were in agreement with the FEA results at sixth order but not at second and fourth order. (5) Although the core needed to be divided in the circumferential direction in order to increase its size, it was clear that the influence on the torque was small. (6) Use of a divided core is a good solution for enlargement of clawtooth motors.     

EFFECT OF VISCOSITY ON PERCEIVED SWEETNESS INTENSITY OF SWEETENED SODIUM CARBOXYMETHYLCELLULOSE SOLUTIONS

To establish a relationship between perceived sweetness intensity (Y), sucrose concentration (A%) and viscosity of mixed solutions (B poise), mixtures of sucrose solutions in various concentration and sodium carboxymethylcellulose with medium viscosity (CMC–M) in various concentrations were used, resulting in the equation: where "Y"= sucrose concentration of reference solutions. This equation was effective within the ranges of 4% to 16% sucrose and viscosities of from 1 to 100 poises. This equation was applicable to low and high as well as medium viscosity forms of CMC.     

Computational complexity of spline interpolation

The procedure for composing the spline function of order m that interpolates n data is roughly divided into two stages: (1) constructing the matrix A_n that transforms the fl-spline coefficient vector c into the sample value vector s; and (2) calculating the vector c. Then the effects of boundary conditions and the locations of the sampling points and the knots on the number of computations for spline interpolation are evaluated. There are no boundary condition effects of the construction of A" for equispacing. Non-periodic boundary conditions reduce the number of computations needed to calculate c from O(m²n) to O(m²n/4).

In the construction of A_n, choosing equispaced sampling points reduces the number of computations from O(m²n) to O(m²) in the case of sampling points located at a constant interval between each pair of adjacent knots. In the calculation of c, equispaced sampling points reduce the number of computations from O(m²n) to O(m²n /2) in the case where m is even and the locations of the knots are identical with those of the sampling points.     

船用柴油机NOx等有害排放气体的评价及处理研究--燃料喷射系统对乳化燃料在船用柴油机上使用的影响及脱硝装置的适用性

对原试验用柴油机的燃料喷射系统进行了改造。改造后的燃料喷射系统不仅可降低 NOx 的排放 ,而且使高加水率乳化燃料的使用成为可能。但另一方面 ,在低负荷时 ,使用乳化燃料不但不能获得预期的降低 NOx 排放效果 ,反而使其它有害排放增加。所以 ,也对降低 NOx 排放方法之一的脱硝装置进行了探讨 ,对其在船用柴油机上的适用性进行了试验 ,并获得了较好的效果     

Direct imaging in a water layer of human chromosome fibres composed of nucleosomes and their higher-order structures by laser-plasma X-ray contact microscopy

X-ray contact microscopy with a 300-ps-duration laser-plasma X-ray source has been used to image hydrated human chromosomes. Clearly imaged are individual nucleosomes and their higher-order particles (superbeads), elementary chromatin fibrils c. 30 nm in diameter and their higher-order fibres of various sizes up to c. 120 nm in diameter. The results demonstrate that X-ray microscopy is now capable of opening a new path of investigation into the detailed structures of hydrated chromosome fibres in their natural state.     

Subsolidus Phase Equilibria in the System Na2O-Bi2O3-TiO2 at 1000°C

Subsolidus phase relations in the system Na₂O-Bi₂O₃-TiO₂ at 1000°C were investigated by solid-state reaction techniques and X-ray diffraction methods. Five ternary compounds were observed in the system: Na_0.5Bi_4.5Ti₄O₁₅; Na_0.5Bi_0.5TiO₃; a cubic pyrochlore solid solution composed of xNa₂O.25Bi₂O₃.(75−;x) TiO₂ where x is 2.5 to 3.75; a new compound Na_0.5Bi_8.5Ti₇O₂₇ indexed with the orthorhombic cell of a = 5.45, b = 5.42, and c = 36.8 Å; and an unidentified phase with the probable composition NaBiTi₆O₁₄.     

The optimal smoothing estimators based on the Wiener-Hopf theory

It is well known that the Wiener-Hopf theory plays a fundamental role in estimation problems. In this paper, we derive the basic equations for the optimal smoothing estimators by using the Wiener-Hopf theory. The interrelation between the Wiener-Hopf theory and the innovation theory is also considered. Finally based on the basic equations three kinds of the smoothing estimators, that is, the fixed-point, fixed-interval, and fixed-lag smoothing estimators are derived.     

Ultra-High-Speed Performance of Ball Bearings and Annular Seals in Liquid Hydrogen at Up to 3 Million DN (120,000 rpm)©

The ultra-high-speed performance of a hybrid ceramic 25-mm-bore ball bearing, as well as that of floating-ring seals with a sealing diameter of 30 mm, was determined in liquid hydrogen at speeds to 120,000 rpm, 3 million DN, under thrust loads to 3,140 N and sealed pressures to 1.7 MPaG. The bearings had Si₃N₄ balls and a single outer land-guided retainer. The hybrid ceramic bearing exhibited excellent performance at high load, contrasting with the seized all-steel bearing; however, the ceramic balls developed superficial micro-cracks due to frictional heating. Effective cooling of the bearing was achieved by increasing the jet speed through the nozzles. The bearing power loss drastically increased with increasing speed and cooling flow rate. The critical load capacity without bearing damage was also evaluated. Furthermore, the sealing performance of the one-ring seal was superior to that of the two-ring seal in preventing the sealing ring seizure against the runner.     

Window functions obtained by convolution integrals of rectangular windows

The rectangular, triangular, and Parzen windows, which have been defined independently of each other, are obtained by repeating convolution integrals of the rectangular window with itself. They are extended to make a series of window functions. This series has the advantage that the sidelobe fall-off is variable though it has the disadvantage that the mainlobe band-width for the same highest sidelobe level is 1–1·3 times those of the gaussian, Kaiser, Dolph–Chebyshev or Blackman–Harris windows. Moreover, this series has a desirable mainlobe bandwidth of 0·85–1 times that of cos^x x windows for the same highest sidelobe level and sidelobe fall-off. Thus, this series is useful in designing window functions whose mainlobe bandwidth is in between that of the gaussian or Kaiser windows and that of cos^x x windows and whose sidelobe fall-off is as good as that of the cos^x x windows.