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Open access

Liang-xiong Dong, Yi-ran Shi and Shao-hua Wang

Abstract

The anti-impact ability of shafting affects stability and security of the ship power transmission directly. Moreover, it also cannot be ignored that the rub-impact loads have influence on the torsion vibration of ship shafting. In order to solve the problem of engineering application of reliability assessment under rub-impact loads, a test rig with rubbing generator is established. By carrying out the integrative analysis, the torsional vibration characteristics, such as vibration amplitude and orbit of axle center under the rub impact load are studied. According to the rub-impact conditions obtained through numerical simulation, the experimental verification is carried out on the test rig with rubbing generator. The results show that it is not obvious the influence of rub-impact loads upon the shafting torsion vibration except in special working conditions, that can be simulated by the rubbing generator. The maximum amplitude of torsional vibration is influenced by the radial rigidity as well as the friction coefficient of rubbing body, and the degree of influence is difference under conditions of continuous rubbing and serious rubbing. By adjusting the rigidity of stern bearing, the influence of rub-impact upon shafting can be weaken, which provides a theoretical reference for the safety evaluation of ship shafting.

Open access

Hongbo Qiu, Wenfei Yu, Cunxiang Yang and Ran Yi

Abstract

In order to compare the performance difference of the permanent magnet synchronous motors (PMSM) with different rotor structure, two kinds of rotor magnetic circuit structure with surface-mounted radial excitation and tangential excitation are designed respectively. By comparing and analyzing the results, the difference of the motor performance was determined. Firstly, based on the finite element method (FEM), the motor electromagnetic field performance was studied, and the magnetic field distribution of the different magnetic circuit structure was obtained. The influence mechanism of the different magnetic circuit structure on the air gap flux density was obtained by using the Fourier theory. Secondly, the cogging torque, output torque and overload capacity of the PMSM with different rotor structure were studied. The effect mechanism of the different rotor structure on the motor output property difference was obtained. The motor prototype with two kinds of rotor structure was manufactured, and the experimental study was carried out. By comparing the experimental data and simulation data, the correctness of the research is verified. This paper lays a foundation for the research on the performance of the PMSM with different magnetic circuit structure.

Open access

Hongbo Qiu, Xiaobin Fan, Ran Yi, Jianqin Feng, Jie Wu, Cunxiang Yang and Haiyang Zhao

Abstract

The major reasons that cause the damage of damper bars in the leeward side are found in this paper. It provides a route for the structure optimization design of a hydro generator. Firstly, capacity of a 24 MW bulb tubular turbine generator is taken as an example in this paper. The transient electromagnetic field model is established, and the correctness of the model is verified by the comparison of experimental results and simulation data. Secondly, when the generator is operated at rated condition, the eddy current density distributions of damper bars are studied. And the asymmetric phenomenon of the eddy current density on damper bars is discovered. The change laws of the eddy currents in damper bars are determined through further analysis. Thirdly, through the study of eddy current distributions under different conditions, it is confirmed that the stator slots and armature reaction are the main factors to affect the asymmetric distribution of the eddy current in damper bars. Finally, the studies of the magnetic density distribution and theoretical analysis revealed the asymmetric distribution mechanism of eddy current density.

Open access

Yang He, Vijaya Pasapula, Xiang Li, Ran Lu, Bei Niu, Pei Hou, Yi Wang, Ying Xu and Fang Chen Chen

Abstract

An efficient system for Agrobacterium tumefaciensmediated transformation of Jatropha curcas was developed in this study. Several factors affecting the transformation efficiency were optimized, including the explant type, preculture and coculture periods, usage of acetosyringone and density of A. tumefaciens. Compared with other explants, 2-day precultured and cocultured hypocotyl explants showed a significant GUS transient expression efficiency (67.7%). Moreover, adding AS showed a remarkable increase in transformation efficiency. After infecting with A. tumefaciens, hypocotyl explants were subjected to expansion and proliferation on MS medium with 1.0 mg· l-1 IBA and 0.5 mg· l-1 BA. Transformants were demonstrated by the GUS assay and PCR analysis. Rate of hypocotyl explants forming resistant calli reached 67.08%. Furthermore, in the transformed calli development, morphologic changes (calli superficial development and internal structure) were observed by SEM and LM. The present study has provided a fundamental information and research approach for the future study of inducing new traits to J. curcas and genetic modification.

Open access

Yi-Ming Zhang, Dong-Xu Yu, Bai-Shuang Yin, Xin-Ran Li, Li-Na Li, Ya-Nan Li, Yu-Xin Wang, Yu Chen, Wen-Han Liu and Li Gao

Abstract

Introduction: Xylazine, a type of α2-adrenoceptors, is a commonly used drug in veterinary medicine. Xylazine-induced changes in the content of amino acid neurotransmitters – glycine (Gly) and aspartic acid (Asp), in different brain regions and neurons were studied.

Material and Methods: Wistar rats were administered 50 mg/kg or 70 mg/kg of xylazine by intraperitoneal injection. In addition, in vitro experiments were conducted, in which neurons were treated with 15 μg/mL, 25 μg/mL, 35 μg/mL, and 45 μg/mL of xylazine. Test methods were based on the enzyme-linked immunosorbent assays (ELISA).

Results: During anaesthesia, Asp levels in each brain area were significantly lower compared to the control group. Except for the cerebrum, levels of Gly in other brain areas were significantly increased during the anaesthesia period. In vitro, xylazine-related neuron secretion of Gly increased significantly compared to the control group at 60 min and 90 min. Moreover, xylazine caused a significant decrease in the levels of Asp secreted by neurons at 20 min, but gradually returned to the level of the control group.

Conclusion: The data showed that during anaesthesia the overall levels of Asp decreased and overall levels of Gly increased. In addition, the inhibitory effect of xylazine on Asp and the promotion of Gly were dose-dependent. Our data showed that different effects of xylazine on excitatory and inhibitory neurotransmitters provided a theoretical basis for the mechanism of xylazine activity in clinical anaesthesia.