Winding Method to Reduce Vibration and Loss Caused by Fractional Slot of Synchronous Machine

Fractional‐slot windings are widely used in rotating machines in order to improve the output voltage waveform, increase the design flexibility, and gain many other advantages. However, fractional‐slot windings are known to produce different harmonic components such as an even order and/or fractional number of space flux harmonics compared to integral‐slot windings. These harmonics may increase stray losses and cause stator core vibration. This paper describes an analysis of space flux harmonics and proposes new winding methods such as “novel interspersed windings” to reduce these harmonic components. The proposed winding methods were verified by numerical analysis and model tests.     

纯铁、铝镇静钢和钛镇静钢的界面特性机理

为了解铝和钛的氧化物在钢中的行为及其夹杂物的去除方法,采用静滴法在1873K及不同氧分压条件下,测定了纯铁、铝镇静钢和钛镇静钢在Al2O3和MgO垫片上的接触角,确认了液滴尺寸与接触角的关系及影响界面张力的因素,并提出了界面行为中线能量的重要性。     

Influence of Porosity on Deformation and Fracture of UO2

The effects of porosity on the deformation characteristics of sintered polycrystalline UO₂ were determined at 500°, 1250°, and 1600°C at a strain rate of ∼0.1 h⁻¹. At 500°C, fracture was brittle and transgranular and initiated from the large pores present after fabrication. An increase in porosity from 5 to 16 vol% caused a 79% reduction in strength. At 1250° and 1600°C, plastic deformation preceded fracture, and the effect of porosity was much more complex. At 1250°C, an increase in porosity increased the strength but lowered the ductility, and the fracture mode changed from intergranular to transgranular. In contrast, at 1600°C porosity had little effect on strength. This behavior was associated with the relative magnitudes of the stress necessary to extend a preexisting flaw and the yield stress and their influence on the brittle-to-ductile transition temperature, T_c.     

Note EXTRACTION EQUILIBRIUM OF MERCURY(II) FROM AQUEOUS AMMONIUM THIOCYANATE SOLUTION WITH TRIISOBUTYLPHOSPINE SULFIDE

The extraction equilibrium of mercury(II) from aqueous ammonium thiocyanate solution with triisobutyl-phosphine sulfide(=TIBPS=S¯) in toluene has been measured at 303 K. It was found that mercury(II) is extracted according to a solvation reaction by TIBPS as a mercurydl) :TIBPS 1:2 complex, Hg(SCN)₂S2, as follows:

The extraction equilibrium constant, K_e, was evaluated as K_e = 1.8 × 10⁶ (dm³/mol)².     

Adaptive least squares method for estimation of partial cloud coverage within a pixel

A study of the estimation of partial cloud cover within a pixel has been conducted in order to be able to use pixels partially contaminated with cloud in sea surface temperature determination.

The existing estimation methods based on the least squares method with constraints of minimizing the mixing ratio and observation vector, are theoretically compared and then an adaptive least squares method is proposed. In a comparative study the estimation accuracies for the proposed and other existing methods, including the maximum likelihood method, are compared with simulated and real satellite image data of NOAA AVHRR and MOS-1 VTIR. The results with the simulation data show that the maximum likelihood method is best followed by the adaptive least squares method, the least squares method and the observation vector, while the results with the real VTIR data show that the proposed adaptive least squares method is best followed by the least squares method, the maximum likelihood method and the observation vector but there is no significant differences between all these methods.     

Preparation of transition metal–carbon material from polyacrylonitrile incorporated with inorganic salts

The incorporation of CoCl₂ and FeCl₂ into polyacrylonitrile (PAN) modified the carbonization behaviour and led to the development of carbon with a narrow pore radius ranging from 1.8–2.3 nm and a high surface area ranging from 182–190 m² g^-1. The carbon obtained was of better structural organization than from the original PAN, having an interlayer spacing, d ₀₀₂, of 0.342 nm and a crystallite dimension along the c-axis, L _c, of 5.5–8.5 nm. The transition metals incorporated into carbon exhibited a strong resistance to hydrochloric acid solution treatment, suggesting high dispersion and strong anchoring of the transition metals in the carbon matrix. These non-crystallized and homogeneously distributed transition metals in carbon seem to promise some interesting applications, for example as supports in catalysis. This revised version was published online in November 2006 with corrections to the Cover Date.     

EFFECT OF PARAMETER CHANGES ON THE PERFORMANCE OF SOLID ROTOR THREE-PHASE RELUCTANCE MOTORS

ABSTRACT

An adequate understanding of the close relation existing between performance characteristics and machine parameters is essential for designing any reluctance motor.

The present paper deals mainly with how the steady-state stability of small solid rotor three-phase reluctance motors is affected by the machine parameters. The effects of certain typical machine parameters have been quantitatively demonstrated, which may be instrumental in designing the motor.

To confirm the results obtained, a comparative review of calculated and experimental values is also presented for a number of different machines.     

Development of integrated production scheduling system for iron and steel works

The primary purpose of production scheduling at an integrated iron and steel works is to establish and execute the optimum production schedule that can improve both productivity and yield at each of the plants such as the steelmaking plants and rolling mills, while giving first consideration to the keeping of the date of delivery

However, it is by no means a simple matter to establish and control an integrated or consistent production, schedule covering about ten production processes for various products with an annual output of 6 million tons or more, or about 26 000 orders monthly

In our system-development efforts, therefore, we made the system under study simple and usable in practical applications, designed a scheduling simulator capable of policy selection, and thereby successfully developed an integrated production scheduling system centring around the scheduling simulator.     

Trajectory Design of Galvano Scanner Considering Voltage Constraint of Current Amplifier

This paper proposes a new method for designing feedforward inputs for Galvano scanners in laser drilling machines. The heat generated by current amplifiers becomes a problem as the positioning speed of the Galvano scanner is increased. The proposed method involves the use of a final‐state control that considers the voltage constraint of a current amplifier. By constraining the applied voltage to the motor, the power supply voltage of the current amplifier is reduced. Therefore, the electricity consumed and the heat generated by the current amplifier can be reduced. The effectiveness of the proposed method is shown through simulation and experimental results.     

Electrical Conduction of Rare-Earth-Doped BaTiO3 Single Crystals

The effect of 0.2 to 0.8 at.% rare-earth ions on the conductivity of melt-grown BaTiO₃ crystals was studied by optical absorption, luminescence, Hall coefficient, and electrical conductivity measurements. The conductivity is proportional to the dopant concentration in these crystals; such is not the case in BaTiO₃ ceramics. A rare-earth ion substitutes on the Ba²⁺ site and yields a donor.