Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 3

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Analysis of low saliency ratio and torque characteristics of the fractional slot concentrated winding Surface mounted motors

Qiu Hongbo, Wang Dong, Yang Cunxiang, Wang Kun

Archives of Electrical Engineering

2024

Vol. 73, nr 1

165--182

In recent years, fractional slot concentrated winding permanent magnet synchronous motors (FSCW PMSMs) have become a hotspot in the research field. Due to the unique inductance characteristics of the FSCW PMSM, a fast and accurate calculation of the d/q-axis inductance and saliency ratio is necessary. In this paper, a method is proposed to calculate the d/q-axis reactance of the FSCW SPMSM, which constructs the equivalent magnetic circuit model of the d/q-axis armature reaction flux separately, and the saliency ratio characteristics of the FSCW SPMSM were demonstrated. In addition, to meet the high requirements of the modern industries, especially in servo systems, accurate consideration of the effect of stator resistance on torque and electromagnetic performance is important and more applicable. According to the relationship between the vector parameter, the explicit expression of the d/q-axis currents that consider the stator resistance is obtained, and the prediction of load angle at maximum electromagnetic torque is achieved. Then, combined with the finite element method, the influence mechanism of stator resistance on the motor steady-state performance is revealed. Finally, the experimental data are compared with the calculation data, and the correctness of the models and analysis was verified.

Influences of process water chemistry on reverse flotation selectivity of iron oxides

Tang Min, Wang Dong, Wu Yan, Liu Dianwen

Physicochemical Problems of Mineral Processing

2022

Vol. 58, iss. 6

art. no. 151839

It is critical for water quality in flotation as it dramatically influences the chemical/electrochemical properties of mineral surfaces and their interactions with reagents. Many potential variations could alter the water chemistry: water recirculation, mineral dissolutions, reagent additions, etc. This study aimed to identify the key elements from the recycled water sources affecting the separation efficiency in a typical industrial flotation circuit of iron oxides through a series of bench/micro flotation tests, zeta potential measurement, etc. The built-up and distribution of the dominant cations/anions in the process water from the roughers in the flotation system was also analyzed and recorded by Inductively Coupled Plasma-Optical Emission (ICP-OES) for a period of about three months when the operations were stable. The flotation results pointed out that a concentrate with a sharp increase of 6.0% Fe recovery and 2.5% SiO2 content was obtained by using the recycled tailing water only in comparison by using fresh water. In contrast, a slight uptrend in the grade of Fe but a substantial loss of near 6.5% Fe recovery occurs by using the treated sewage water alone instead. This could attribute to the ion distributions in these water sources, in which Ca2+, Fen+, Mg2+ or SO42ions were determined as the key ions influencing the flotation behaviors of the iron ore. But the competitive effects of Fe3+ ions were more significant than the ones of Ca2+ or Mg2+ ions. And the occurrence of starch could deteriorate the dilution of silicates in concentration induced by Fe3+/Fe2+ ions. It can be explained by zeta potential measurement or solution chemistry of those ions, indicating that at 8.5-9.0, the coating of the precipitates of Fe(OH)3(s) induced by iron ions alters a reverse on the zeta potentials of quartz. The presence of SO42-ions, however, has a positive role in reducing the possibility of slime coating on silicates due to acting as a chelating agent of iron ions.

Energy characteristics and micro cracking behaviors of deep slate rock under triaxial loadings

Zhang Anlin, Feng Tao, Jiang Liangwen, Wang Dong, Wang Zhewei, Zhang Ru, Feng Gan, Zhang Zhilong, Deng Jianhui, Ren Li

Acta Geophysica

2022

Vol. 70, no 4

1457--1472

Sichuan-Tibet railway tunnels are generally long and deep, and some of them pass through layered slate, which is prone to failure under high in situ stress. Insight into the mechanical behaviors of deep slate under different stress environments is critical to the safety of engineering practices in this area. To this end, we studied the energy characteristics and microcracking behaviors of slate samples under different triaxial loadings. The results showed that the confining pressure increased the strength, elastic modulus, Poisson’s ratio and crack characteristic stresses of the studied slate. As the confining pressure increased, the storage of elastic strain energy during the prepeak stress stage increased, and its release during the postpeak stress stage was inhibited. Additionally, we obtained the slate failure precursors by analyzing the acoustic emission (AE) evolution characteristics, i.e., “a sudden increase in AE metrics, followed by a quiet period, and then a sudden increase again” in terms of the AE count rate and AE energy rate after obvious expansion of the sample. Then, we further observed that with an increase in confining pressure, a gradual transition of the failure pattern from compressive shear to tensile shear occurred. Finally, we discussed the influence mechanisms of confining pressure on the slate failure behaviors and concluded that the change in the effective shear stress along the foliation planes played an important role in the failure mode transition.